University of Kansas Publications

Museum of Natural History

Vol. 4, pp. 1-466, plates 1-41, 31 figures in text

December 27, 1951

AMERICAN WEASELS

BY

E. RAYMOND HALL

University of Kansas

Lawrence

1951

University of Kansas Publications, Museum of Natural History

Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor, Robert W. Wilson

Vol. 4, pp. 1-466, plates 1-41, 31 figures in text

December 27, 1951

University of Kansas

Lawrence, Kansas

PRINTED BY

FERD VOILAND, JR., STATE PRINTER

TOPEKA, KANSAS

1951

23-3758

Plate 1.

Coloration of head and foreparts in ten subspecies of long-tailed weasel, Mustela frenata. All figures are of males, approximately × 1/2.

In regions of heavy rainfall (see figs. 2 and 3) there is an increase in pigmentation and extent of blackish color backward over the neck and a decrease in extent of the white facial markings. In regions progressively more arid (see figs. 3 to 7) there is a decrease in pigmentation and extent of blackish color and an increase in extent of the white facial markings.

As shown by rearing mammals from humid regions in arid regions, and vice versa, the color is not visibly altered in one or a few generations; the color is an hereditary character. Beginning with the southernmost subspecies (fig. 1) and continuing northward to the northern subspecies (fig. 10) there is a darkening, next a lightening, and finally a darkening closely conforming to amounts of precipitation in the geographic regions concerned. A fuller discussion of this correlation is given on page 51.

Fig. 1. Map showing localities of capture of specimens depicted in plate 1.

American Weasels

BY

E. RAYMOND HALL

CONTENTS

American Weasels

By E. Raymond Hall

INTRODUCTION

The weasel's agility and speed take it in and out of retreats, over obstacles and across open places in amazingly rapid fashion and are responsible for the animal's actions being described as "quick as a flash." The common long-tailed weasel of the United States measures approximately a foot and a half in length, of which the tail comprises a third; but the round, slender body is scarcely more than an inch and a half in diameter. Brown above and whitish below in summer dress, the animal is sleek as well as lithe and graceful. It is easy to understand, therefore, why the Bavarian name Schönthierlein (pretty little creature) and the Italian name donnola (little lady) were bestowed upon it. The Spanish name is comadreja (godmother).

In the winter, in temperate and northern regions, the coat becomes pure white except for the black tail-tip. In this dress the correct name for the animal is ermine, a mammal whose fur is known to all and justly esteemed, especially for its luster in artificial light, where it is scarcely excelled in enhancing the beauty of gems and their feminine wearers.

In relation to its weight, the weasel is thought to be unsurpassed, and perhaps it is unequalled among mammals, in the effectiveness with which it exercises its carnivorous heritage; it kills with speed and strength a wide variety of animals including many much larger than itself; and it has been known to attack even man himself when he stood between the weasel and its intended prey. In structure and temperament it is so highly specialized for offense that, when opportunity affords, it sometimes kills, for storage in its larder, far more than enough to meet its immediate needs. After speaking of this tendency, Elliott Coues (1877:129) has said:

"A glance at the physiognomy of the weasels would suffice to betray their character. The teeth are almost of the highest known raptorial character; the jaws are worked by enormous masses of muscles covering all the side of the skull. The forehead is low and the nose is sharp; the eyes are small, penetrating, cunning, and glitter with an angry green light. There is something peculiar, moreover, in the way that this fierce face surmounts a body extraordinarily wiry, lithe, and muscular. It ends in a remarkable long and slender neck in such a way that it may be held at right angle with the axis of the latter. When the creature is glancing around, with the neck stretched up, and flat triangular head bent forward, swaying from one side to the other, we catch the likeness in a moment—it is the image of a serpent." Although Coues' colorful description more closely links the weasel with the symbol of evil than pleases me, his description does emphasize the raptorial character of the weasel.

Even though most weasels are intractable as pets, they have a value to man, as, for instance, when he is plagued by mice. In a field where mice and other small rodents are so abundant as to damage cultivated crops, the weasel is the farmer's best friend. A weasel may inhabit one den until the rodents thereabouts are almost exterminated in an area two or three hundred yards across; in this way the weasel acts as a control, locally, as well as a check more widely, on the increase in size of populations of kinds of rodents upon which it preys. The smaller species are mousers of remarkable efficiency and can, if necessary, follow a mouse to the end of the mouse's burrow. The slender body allows the weasel to pass through any burrow or hole into which it can thrust its head. This ability in an organism as highly specialized for killing other animals as is the weasel, has earned for it a bad name in connection with poultry yards. Authentic instances are recorded in which a weasel, gaining entrance through a knot-hole to a coop of young chickens, killed several dozen of the fowls. In other instances, however, weasels have lived under buildings close by a poultry yard without even molesting the birds in the slightest; in the latter instances the weasels probably were present because there was an abundant supply of rats and mice. At least three poultry raisers (see page 214) have encouraged weasels to live in their poultry yards feeling that the good they do by destroying rats outweighs the damage caused by the occasional weasel which turns to the fowls; the idea is that the individual weasel can be eliminated if he becomes destructive.

Although tending to be nocturnal, weasels are almost as active by day as by night. Their young, numbering 4 to 9, are born in a nest in a burrow and as with other members of the Order Carnivora, are blind, and incapable of looking after themselves at the time of birth. In Mustela frenata of Montana, breeding occurs in July and August, and the young are born in the following April and May. Wright (1948A:342) showed that the gestation period could not have been less than 337 days in one individual and that it averaged 279 (205-337) days in 18 instances. Findings of the same author (1942B:109) showed that the embryos are implanted only 21 to 28 days before the young are born. In the preceding part of the "long gestation period, the embryos lie dormant in the uterus as un-implanted blastocysts. The young female weasel [of M. frenata] mates when 3 or 4 months old." Consequently, in the spring, all females of this species may produce young (Wright, 1942A:348). The circumboreal species Mustela erminea likewise has been shown to have a delayed implantation of the ova. Each of these two species, M. frenata and M. erminea, has only one litter per year; but the weasel, Mustela nivalis, of the Old World seems to lack the delayed implantation, in this respect resembling the ferret (subgenus Putorius) as it does also in its ability to have more than one litter per year (see Deanesly, 1944). The manner of reproduction in the South American species M. africana and the circumboreal species M. rixosa at this writing is unknown.

The genus Mustela includes the true weasels, the ferrets and minks. The ferrets commonly are treated as a subgenus, Putorius, along with the Old World polecat. The minks usually are accorded subgeneric distinction under the name Lutreola, and the true weasels comprise the subgenus Mustela, the three subgenera together, along with some other subgenera which are mostly monotypic, comprising the genus Mustela. Considered in this way, the group of true weasels, subgenus Mustela, has a geographic range roughly coextensive with that of the genus Mustela. This range includes Asia and Europe, Northern Africa, North America and northern South America. Java has its weasel. Australia and nearly all the oceanic islands lack weasels, and the animals are absent from roughly the southern half of Africa and the southern half of South America. Other small mustelids, weasellike in shape and with corresponding habits and dentition, take the place of true Mustela in the southern half of Africa and in the corresponding part of South America.

In America the subgenus Mustela occurs from the northernmost land in Arctic America southward to Lake Titicaca in the Andes of South America, a distance of approximately 6900 miles. Felis, I think, is the only other genus of land mammals in the western hemisphere that has a geographic range as extensive from north to south. Felis does not range so far north but does range farther south. The one species, Mustela frenata, ranges from Lake Titicaca northward to about 57° N in British Columbia or for approximately 5000 miles in a north to south direction and from within the Alpine Arctic Life-zone through the Tropical Life-zone. In North America, weasels occur in almost every type of habitat, being absent only in the extremely desert terrain of western Arizona and western Sonora and in adjoining parts of California and Baja California. Even this area, along the Colorado River, may support some weasels; evidence suggesting that it does so is given in the account of Mustela frenata neomexicana.

PALEONTOLOGICAL HISTORY

The paleontological record fails to show the precise ancestry of Mustela. The genus has been found in deposits of Pleistocene age, but, so far as I can ascertain, not in deposits of earlier times. The Pleistocene remains are not specifically distinct from Recent (living) species, and in only a few instances (see M. f. latirostra and M. e. angustidens) are they even subspecifically distinct from the Recent weasel living in the same area today. It is true that fossil remains from deposits of several stages of the Tertiary beds have in the past been identified in the literature as Mustela, but most of these identifications were made many years ago when the generic name Mustela was used in a far broader and more inclusive sense than it is today and much of the fossil material was so fragmentary that the generic identity could not be ascertained, at least at that time. Because the generic identity could not be ascertained, the fossil material was tentatively assigned to the genus Mustela, the "typical" genus of the family Mustelidae instead of to some other more specialized or less well-known genus of the family. To satisfy my curiosity about these species of "Mustela" of a geological age earlier than the Pleistocene I have personally studied nearly all of the original specimens from North America and have found each to be of some genus other than Mustela. Also, such study as I have been able to make of the Old World fossils themselves that have been referred to the genus Mustela up to 1938, and my study of the illustrations and descriptions of the others from there lead to the same conclusion; that is to say, none that is true Mustela is known up to now from deposits older than the Pleistocene.

When, in 1930 (pp. 146-147), I wrote about the taxonomic position of three American genera of fossils (known only from lower jaws), each of which had been previously referred to the genus Mustela, I said that they pertained "to that section of the weasel family (Mustelidae) which comprises the polecats, true weasels, ferrets, minks and martens. The fossil specimens . . . are smaller than any other later Tertiary members of the group yet described, and are more primitive than any of the above mentioned Recent relatives. Of the three extinct genera . . . Miomustela [Lower Pliocene or Upper Miocene of the Lower Madison Valley, Montana] is the most primitive and Martinogale [Pliocene, 18 mi. SE Goodland, Sherman County, Kansas] is the most advanced. This view rests largely on the character of M₌₁ which in Miomustela has a deeply basined, short, narrow talonid with a thick, high metaconid situated partly posterior to the protoconid. In Martinogale the talonid is incipiently trenchant, long, broad, and it has a lesser developed metaconid which is situated more anterior [ly]. Pliogale [Lower Pliocene, Humboldt County, Nevada] is intermediate in this respect.

"These three forms are of special interest as possible ancestors of the subgenus Mustela, true weasels. No members of this subgenus, nor related forms which can with any degree of certainty be regarded as directly ancestral to them, have yet been described from Miocene or Pliocene deposits. Palaeogale of the Old World and Bunaelurus of North America, each of Oligocene age, have been placed by Schlosser (1888, p. 116) and Matthew (1902, p. 137) as members of the primitive group of mustelids ancestral to Mustela. This course seems logical; and with no truly intermediate links between these forms of the Oligocene on the one hand, and Mustela which first appears in the Pleistocene, on the other, more definite statements about ancestral positions of the small Oligocene forms can hardly be made. The deciding considerations for authors who placed Palaeogale and Bunaelurus as ancestral to Mustela were the absence of a metaconid on M₁ and the trenchant talonid of that tooth. These characters are found also in Mustela. On the other hand certain structures in the basicranial region of Palaeogale and more especially of Bunaelurus indicate that these genera possibly are not close to the ancestral form of Mustela . . . Martinogale may stand near the ancestral form of Mustela and . . . Pliogale may be ancestral to Martinogale. Pliogale, in turn, may have had an ancestor similar to Miomustela. If this should prove to be the case, Palaeogale and Bunaelurus might be regarded as an independent branch which displays merely a parallelism to Mustela in the loss of the metaconid on M₁ and the development of a trenchant talonid on that tooth. The writer would make it clear that he does not hold such to be the case. The ancestral relation of Martinogale to Mustela is presented merely to show the possibility, and not the special probability, of such an origin for Mustela. Knowledge of the tympanic bullae and other structures of the basicranial region would go far toward answering the question and until these structures are known [in mustelids of the Later Tertiary,] some uncertainty will remain."

At the present writing I can add to the above statement only a few facts. The discovery of better material of Bunaelurus than was available to previous workers led Simpson (1946), correctly I think, to synonymize Bunaelurus with Palaeogale. Simpson figures the cranial foramina in Palaeogale. The differences, between Palaeogale and Mustela, in cranial foramina, possibly are only the result of the elongation of the tympanic bullae. The bullae of the subgenus Mustela are seen to be much elongated posteriorly if comparison is made with the bullae of earlier mustelids. Consequently, it might be concluded that there is nothing in the arrangement of the cranial foramina which would preclude the derivation of Mustela from Palaeogale. However, the anterior situation of the carotid foramen—well forward along the medial margin of the tympanic bulla—is a character typical of other mustelids and the posterior location of this foramen in Palaeogale might indicate that it was not ancestral to Mustela.

SKELETON AND DENTITION

The outstanding features of a weasel's skeleton are its length and slenderness. Whereas the length of the vertebral column measured from the atlas (the first cervical vertebra) to the last sacral vertebra is 175 per cent of the length of the hind leg (as measured from the head of the femur to the tip of the longest claw), the corresponding percentage is only 116 in the raccoon. Stated in another way, the vertebral column and the hind leg are of approximately equal length in a raccoon, but in a weasel the vertebral column is one and three-fourths times as long as the hind leg.

VERTEBRAE

The vertebral column consists of 7 cervicals, and ordinarily 14 thoracics, 6 lumbars, 3 sacrals and, depending on the species, 11 to 23 caudals. For the three species of which skeletons were examined, variations from the normal number of vertebrae are noted in the following table:

Table 1
Data on vertebrae in three species of the subgenus Mustela
(Numerals in parentheses indicate number of specimens)

Variation according to the species is evident in the number of caudal vertebrae, but in the other categories of vertebrae no consistent difference in number according to species was found in the material examined. Apparently there is also some geographic variation in the number of caudal vertebrae within a species. For example, the one skeleton seen of Mustela rixosa eskimo (no. 219036, U. S. Nat. Mus., from St. Michaels, Alaska) has only 11 caudal vertebrae, whereas in the 11 Mustela rixosa rixosa from Roseau County, Minnesota, the usual number is 15 with extremes of 14 and 16. Similarly specimens of Mustela frenata from Idaho and California almost always have 1 or 2 more caudal vertebrae than do individuals of the shorter-tailed subspecies of the same species from eastern Kansas.

Of the vertebrae, only the cervicals, of which there are 7, were found to be constant in number. In M. erminea, two of the seven individuals in which the anticlinal vertebra was the 12th (instead of the 11th) had 15 instead of the customary 14 thoracic vertebrae. In M. frenata, seven of the twenty-seven individuals in which the anticlinal vertebra was the 12th (instead of the 11th) had 15 instead of 14 thoracic vertebrae. The one M. erminea with a pseudosacral vertebra had only two instead of the customary 3 sacral vertebrae but the same individual had 15 thoracic vertebrae. Of the six M. frenata with a pseudosacral vertebra, two animals had only two instead of three sacral vertebrae. Conceivably, therefore, the pseudosacral vertebra in each of the three instances mentioned may represent merely an unfused sacral vertebra, instead of a true pseudosacral as occurs in four individuals of M. frenata.

TEETH

In American weasels, for example in Mustela frenata, the permanent dentition normally is

  I  3  C  1  P  3  M  1
  -, -, -, -, -, -, -, -
  i  3  c  1  p  3  m  2

or 34 teeth in all. In most respects the dentition is typical for post-Tertiary mustelids but in several parts is highly specialized for a diet of flesh, the degree of this specialization being second only to that of the cats, family Felidae. The outstanding specialization is in the first lower molar, in which, as in the cats, the internal cusp (metaconid) is completely suppressed and the heel (talonid) forms an elevated blade for cutting food rather than a basin for crushing it. In one sense the tooth is simplified since it owes its distinctive form to a reduction in number of parts; nevertheless, the distinctive form of the lower molar clearly is correlated with a diet of flesh, and the tooth is correctly to be thought of as the lower blade of a pair of shears; the upper blade is the fourth upper premolar. The reduction in size of the second (last) lower molar and small size of the inner lobe of the one remaining upper molar probably are additional modifications for a diet of flesh.

The absence of the last two upper molars and last molar in the lower jaw would be expected in any mammal as highly specialized for a diet of flesh as is the weasel, but these teeth are absent also in other Quaternary members of the family Mustelidae, many of which are substantially less specialized for a diet of flesh than is the weasel. Therefore, in the weasel, it is reasonable to regard the absence of these teeth more as a heritage than as an indication of a special adaptation. The absence of a first premolar above and below, as in the weasel, is to be expected in any carnivore that has the first lower molar and fourth upper premolar highly specialized for shearing, but the loss of these premolars and the small size of the second premolars may be as much the result of a slight shortening of the face as it is a result of a lengthening of the third and especially the fourth premolars. The lengthening of these more posteriorly-situated teeth would appear to be an adaptation to a diet of flesh. The cause of the lengthening of the mentioned teeth and the reason for the absence of the first premolars probably will be unknown until the fossil record is more complete.

The teeth of American species vary little except in size. The absence of P2 in Mustela africana is the only difference of a qualitative (presence or absence) nature that was detected. Also, the Central American subspecies of Mustela frenata exhibit a tendency to early loss of P2 and thus foreshadow the condition typical of M. africana.

As a whole the dentition of the weasel exhibits a high degree of specialization for a diet of flesh and this specialization is fully as evident in the deciduous dentition as in the permanent dentition.

The deciduous, or milk, dentition, of Mustela frenata, as known from immature specimens of Mustela frenata noveboracensis and Mustela frenata frenata available for this study, is comprised of canines, one on each side above and below, and 3 cheek teeth on each side above and below. See figures 2-9. The upper cheek teeth from anterior to posterior are: a minute peglike tooth in general similar to the first premolar of the permanent dentition; a shearing tooth in general similar to P4 of the permanent dentition; and an anteroposteriorly compressed tooth in general similar to M1 of the permanent dentition. In the lower jaw, behind the canine, there is first a minute peglike tooth, second a two-rooted tooth similar in general outline to a permanent third premolar, and finally a shearing tooth corresponding in function to m1 of the permanent dentition.

No postnatal specimens which show deciduous incisors have been examined.

Selected, outstanding differences between the permanent teeth and the deciduous teeth are as follows: In the deciduous teeth the canine above has on the posterior face a well-defined ridge extending from the tip to the cingulum. This ridge is absent or at most faintly indicated in the permanent tooth. The lower deciduous canine, in cross section is seen to have a marked indentation on the anteromedial border in the region of the cingulum; this indentation is lacking in the permanent tooth. The anterior one of the deciduous cheek teeth, both above and below, is single rooted and its crown-surface is only about one-fifteenth as much as that of the anterior premolar of the permanent dentition. The second deciduous cheek tooth below has two roots, usually fused, and differs from p4 of the permanent dentition in having the tip of the principal cusp more recurved, in having the anterior basal cusp better developed and the posterior heel less well developed.

The second deciduous cheek tooth above corresponds in function and general plan of construction to P4 of the permanent dentition but differs from that tooth in the more pronounced protostyle, longer tritocone, more posteriorly located deuterocone and as noted by Leche (1915:322) separation of the protocone and tritocone by a notch. The third upper deciduous tooth has a single cusp internally and two cusps laterally. Thus it reverses the relation of parts seen in M1 where the internal moiety is larger than the lateral or buccal moiety. The third deciduous tooth below differs from m1 in very much shorter talonid and separation of the paraconid from the protoconid by a deeper notch.

All the features in which the last two deciduous teeth, both above and below, are described as differing from their functional counterparts in the permanent dentition, are features found in the permanent teeth of primitive fossil mustelids and certain fossil and Recent viverrids. Even so, taking into account Leche's (1915) work, which shows that the milk teeth of some carnivores have structures lacking in the corresponding permanent teeth of the same individual animal and also in the teeth of genera that seem to be ancestral, a person suspects that some of the structural features mentioned above are not inheritances of ancestral conditions but rather specializations of the milk dentition.

Figs. 2-9. Views of permanent and deciduous teeth of Mustela frenata nigriauris. Incisors not shown. In each instance teeth are of the left side.

Permanent dentition × 3. No. 32421, Mus. Vert. Zoöl., ♂, adult; Berkeley, Alameda County, California; obtained October 4, 1921, by D. D. McLean.

Deciduous dentition × 5. No. 132158, U. S. Nat. Mus., ♂, juvenile; Stanford University, Santa Clara County, California; obtained May 7, 1898, by W. K. Fisher.

Figs. 2-3. Lateral views of upper teeth, of adult and juvenile respectively.

Figs. 4-5. Occlusolingual views of upper teeth of adult and juvenile respectively.

Figs. 6-7. Lateral views of lower teeth of adult and juvenile respectively.

Figs. 8-9. Occlusolingual views of lower teeth of adult and juvenile respectively.

In other deciduous teeth there is clearer evidence of more specialization for a diet of flesh in the deciduous teeth than in the permanent teeth. For example, the upper carnassial of the milk dentition is even more highly sectorial than is the permanent tooth and strikingly like that of some of the cats. The lower tooth that is effective in the shearing action bears no more trace of the metaconid than does the permanent first lower molar. These features of the deciduous dentition suggest that it is more specialized for a diet of flesh than is the permanent dentition. If this be the fact, it may seem especially remarkable because the commonly employed term "milk teeth" suggests that the animal makes but little or no use of these teeth in the short time that they are in place. Accordingly, the student may credit the form of these teeth more to some indirect effects of inheritance than to natural selection acting directly upon the teeth. But, after all, natural selection probably is responsible for the form of these teeth as is indicated by the observations of Hamilton (1933:318-325). He found that these milk teeth are used for eating solid food as soon as the principal shearing teeth are in place. This is three weeks after birth and before all of the deciduous teeth have broken through the gums. These shearing teeth are used for almost two months before being replaced by the permanent teeth and it is, therefore, evident that natural selection could operate to fully as great a degree in determining the form of the deciduous teeth as it may with the permanent teeth.

Hamilton (1933:325-326) found that the permanent dentition was complete at 75 days after birth in captive specimens of Mustela frenata noveboracensis. In the same subspecies, he noted 28 days after birth that the canines and carnassial teeth [second deciduous cheek tooth above and third below] had erupted through the gums. Animals 45 days old, Hamilton found, were losing the milk dentition, and had the gums broken through by several of the permanent cheek teeth.

Study of the cleaned skulls available of juveniles indicates that the deciduous teeth which persist longest are, on each side of the mouth, the second cheek tooth above and the third cheek tooth below. These teeth persist until after the permanent P4 and m1 have come into use. These permanent teeth are situated immediately behind their functional counterparts of the milk dentition. P3 and p4 are the teeth of the permanent dentition which ultimately push out the last milk teeth to be lost. Accordingly, in the permanent dentition, P4 and M1 appear before P3 does, and m1 and m2 make their appearance before p4.

DISPARITY IN NUMBERS OF MALES AND FEMALES (IN ZOOLOGICAL COLLECTIONS)

The question has frequently been asked why twice as many male as female weasels are captured. This is the proportion in research collections, as may be seen from table no. 2, and I am convinced that the specimens in these collections are saved in approximately the same proportion as that in which they are caught. Although it might be assumed, upon first consideration, that there are twice as many males as females in nature, selective factors enter into the catch. For example, because a male weasel is approximately twice as heavy as a female, it may be necessary for him, in a given length of time, to travel twice as far as the female to obtain the required amount of food with the result that a given number of traps or snares will catch twice as many males as females. Indeed, Glover (1943B:8) shows that, on the average, in Mustela frenata noveboracensis in Pennsylvania, the male actually does travel slightly more than twice as far as the female (704 feet versus 346 feet). From table no. 2, it may be seen that in most winter months the ratio is 3 males to one female. This ratio is reasonable enough, in view of what has been said, if it is considered also that the lighter weight of the female permits her safely to step on the pans of traps that would be sprung by heavier males.

If in the breeding season, which is April through August in M. frenata, the female is passive and if the male is restlessly searching for her, he may thus increase still more his chances of being caught in traps set for weasels.

My own studies of live weasels in nature indicate that in the season when females are attending young which are half grown, or larger, the adult male weasels live singly in dens of their own, separate and apart from the females and their young (Hamilton, 1933:328, records adult males living with the female and her young, but possibly this was when the young were less than half grown). Perhaps these males at that time travel no farther than is necessary to obtain food for themselves. Females, at this time, forage not only to meet their own needs, but for food to supply their young as well. At this time, in May and June, as may be seen from table no. 2, almost as many adult females as adult males are caught. The reason why only relatively more females than in other months, instead of actually more females than males, are caught at this time probably is that the adult males also are extraordinarily active at this time because they are in breeding condition. Perhaps the explanation in part is to be found in the lesser weight of the female (approximately half of the male's weight) which, as indicated above, permits her to step on the pan of a steel trap without springing it whereas the heavier male does spring the trap and as a consequence is caught. Hamilton (1933:299-300), who mentions this selective factor, found an equal number of males and females in the three newly born litters that came under his observation.

Table 2
Specimens of Mustela frenata (north of the range of M. f. frenata) arranged by sex and under each sex by age

I suppose that in nature there are approximately equal numbers of male and female weasels and further suppose that the selective factors which cause more males than females to be caught are the greater distances traveled by the males and their greater weight.

MATERIALS, ACKNOWLEDGMENTS AND METHODS

At a late stage in the preparation of this manuscript a total of 5,457 specimens had been examined. For the most part these were conventional study-specimens; that is to say, they were stuffed skins with the skulls separate and each was accompanied by the customary data as to locality of capture, date of capture, name of collector, external measurements and sex recorded on the labels by the collectors. Skulls unaccompanied by skins, nevertheless, comprised a large share of the total and a small proportion was made up of skins unaccompanied by skulls, mounted specimens, skeletons, and entire animals preserved in liquid.

It was the recognition of this need for specimens from extensive areas from which no specimens previously had been collected that influenced me, approximately a year after the study was begun, to allot for it a long span of time. The procedure adopted, in general, was to study the weasels of one species from a given geographic area in so far as the material warranted, then lay this aside until additional critical material could be obtained, and finally, some months or a year later, complete the account. In this fashion the manuscript of the American weasels received my attention in each of the past twenty-five years (September, 1926 to date of publication). This is a confession of fact rather than a recommendation of procedure. This type of procedure unduly delays the diffusion of knowledge and for a variety of reasons justifiably annoys other students of the subject. Nevertheless, many gaps have been filled that otherwise would have remained open. Although specimens to solve several problems still remain to be collected and studied, it seems that a point of diminishing returns has now been reached, which, in fairness to all concerned, calls for publication of the results so far obtained.

[22]

For assistance in the entire undertaking, I am more indebted to Miss Annie M. Alexander than to any other one person; she provided the means by which specimens from critical areas were obtained, made it possible to examine the European collections, and assisted in other ways. The late Professor Joseph Grinnell and Mr. Charles D. Bunker, among others, gave truly valuable encouragement and assistance.

Collections containing weasels which were examined in the study here reported upon were as follows:

Acad. Nat. Sciences of Philadelphia American Mus. Nat. History Baylor University Berlin Zoological Museum Boston Society of Natural History Brigham Young University British Museum of Natural History California Academy of Sciences Carnegie Museum Charleston Museum Coe College Collection of J. Arnold Collection of Stanley C. Arthur Collection of Rollin H. Baker Collection of William Bebb Collection of R. H. Coleman Collection of Ian McTaggart-Cowan Collection of Stuart Criddle Collection of John Cushing Collection of Walter W. Dalquest Collection of William B. Davis Collection of J. M. Edson Collection of Ralph Ellis Collection of John Fitzgerald, Jr. Collection of Mr. Green Collection of Ross Hardy Collection of Donald V. Hemphill Collection of L. M. Huey Collection of R. W. Jackson Collection of Stanley G. Jewett Collection of E. J. Koestner Collection of J. E. Law Collection of A. H. Miller Collection of Lloye H. Miller Collection of R. D. Moore Collection of J. A. Munro Collection of O. J. Murie Collection of Robert T. Orr Collection of Arthur Peake Collection of Kenneth Racey Collection of William B. Richardson Collection Rocky Mt. Spotted Fever Lab. Collection of Victor B. Scheffer Collection of William T. Shaw Collection of O. P. Silliman Collection of W. E. Snyder Collection of Frank Stephens Collection of T. C. Stephens Collection of D. D. Stone Collection of Myron H. Swenk Collection of Joe and Dean Thiriot Collection of John Tyler

Collection of Jack C vonBloeker Collection of Alex Walker Collection of Edward R. Warren Colorado Museum of Natural History Charles R. Conner Museum Cornell University Donald R. Dickey Collection Field Museum of Natural History Florida State Museum Fresno State Junior College Humboldt State Teachers College Illinois Natural History Survey Iowa State College Iowa Wesleyan College Kansas State Agric. College Leland Stanford Junior University Leningrad Academy of Science Los Angeles Mus. Hist. Art and Sci. Louisiana State University Mt. Rainier Nat'l Park Collection Museum of Comparative Zoölogy Mus. Polonais d'Hist. Nat., Warsaw Mus. Vert. Zoöl., Univ. California Museum of Zoölogy, Univ. Michigan National Museum of Canada Naturhistoriska Ricksmuseum, Sweden Neuchatel University Museum New York State Museum Ohio State Museum Oklahoma Agric. and Mech. College Ottawa University, Kansas Paris Museum Provincial Museum of British Columbia Royal Ontario Museum of Zoölogy San Diego Society of Natural History State Hist. and Nat. Hist. Soc. Colo. State Normal School, Cheney, Wash. Texas Cooperative Research Collection United States National Museum University of Arkansas Univ. California Mus. Palaeo. University of Idaho Univ. Kansas Mus. Nat. History University of Minnesota University of Notre Dame University of Oklahoma University of Oregon University of South Dakota University of Utah Univ. Washington Museum of Zoölogy University of Wisconsin Univ. Zool. Mus., Copenhagen

[23]

The largest single collection is in the United States National Museum, where the specimens of the National Museum proper and the United States Biological Surveys Collection, together, provide essential materials including a large share of the holotypes. Specimens in all of the North American collections including Canada and México have been made available, by loan, and in 1937 materials were examined in the principal collections of northern and central Europe. After the materials in North American collections were assembled, special effort, with considerable success, was made in each of several winters, to obtain specimens from areas not previously represented in collections.

To the many persons who were in charge of the collections consulted, to those who at my request sought critical specimens, and to those who assisted in various stages of assembling data and in preparation of the manuscript, I am grateful indeed. Likewise, I am deeply appreciative of the grants-in-aid received from the Carnegie Institution of Washington, the University of California Chapter of Sigma Xi, the John Simon Guggenheim Memorial Foundation and the Kansas University Endowment Association. I am mindful also of an obligation to those who appropriated funds, by legislative action, for research use by The University of California and The University of Kansas.

For assistance with the illustrations I am indebted to the late Major Allan Brooks for Plate 1 , to Mrs. Mary Blos for figures 25-31, to Miss Ann Murray for figures 11-13, to Mr. W. C. Matthews for all the photographs, to Mrs. Freda L. Abernathy for figures 2-9, 18-22, 24, and for retouching all the photographs except the following which were retouched by Mrs. Virginia Unruh: figs. d of plates 2, 3, 4, 9, 10, 11, 16, 17; figs. i of plates 5, 6, 7; figs. h, j, k of plate 7; figs. f and g of plates 12 and 13; and figs. c and d of plate 14. To Mrs. Unruh I am further indebted for figures 1, 16, 17 and 23 and for much terminal assistance with preparing most of the illustrations for the engraver.

The methods of study, after specimens were assembled, included first comparisons of specimens of like age and sex from each of several localities to ascertain the constant features by which full species were distinguishable, one from the other. For example, it was found that in every individual from Trout Lake, Washington, of the species here designated Mustela erminea, the postglenoidal length of the skull amounted to more than 47 per cent of the condylobasal length whereas it was less than 47 per cent in all individuals here designated as Mustela frenata, from the same locality. Testing of specimens from other localities by means of this and other selected characters permitted the outlining of the geographic ranges of the full "species-groups." By comparing specimens of other nominal species and by examining specimens from localities geographically intermediate between the nominal species, I found intergradation and therefore arranged the nominal species as subspecies of a single species. Intergradation here is understood to be the result of crossbreeding in nature between two kinds of animals in the area where the geographic ranges of the two kinds meet. Presence of intergradation between two kinds of weasels was basis for according them subspecific rank. Absence of intergradation in nature at every place where the geographic ranges of two kinds met or overlapped, and absence of intergradation by way of some other kind, or chain of kinds, was basis for according each of the two kinds full specific rank. By thus applying the test of intergradation, or lack of it, I found that there were four full species of weasels, of the subgenus Mustela, in all of the Americas.

Next, the specimens of one species were arranged in trays in a geographic sequence. The specimens from any one locality were segregated by sex and under one sex from one place were arranged from oldest to youngest, that is to say by age. The four series with the largest numbers of individuals of a given age were selected. Seventeen cranial measurements and three external measurements were recorded for each individual of each of these four series. For each measurement, the coefficient of variation, standard deviation and probable error were computed. The four samples subjected to such analysis were a series of adult males, one of adult females, one of subadult males and one of subadult females. Also, studies of each sex were made to ascertain seasonal changes in pelage. After data were obtained on ontogenetic (age) variation, secondary sexual variation, seasonal variation, and degree of individual variation by studying specimens in the manner described above, tests were made for subspecific (geographic) variation by comparing series of specimens of like sex, age and season, from different localities. For each one of several geographically variable features noted, a map was prepared for animals of each sex. When all the data thus obtained were codified, subspecific ranges were, in a sense automatically, obtained. On the resulting map showing geographic ranges of subspecies for a species, a type locality was accurately plotted for each name that had been applied to the species, and names then were applied in accordance with the international rules of zoölogical nomenclature.

VARIATION

Variation with Age

The kind of variation which results from increasing age has been dealt with extensively for the skull (of the Old World Mustela erminea) by Hensel (1881) and for the external features and to some extent for the skull by Hamilton (1933) in the North American forms M. erminea cicognanii and M. frenata noveboracensis.

The young of both erminea and frenata are hairless and blind at birth. In M. frenata noveboracensis, the eyes open on approximately the 37th day. When 2 to 4 months old, the tail is pointed at the tip. This is because the terminal hair of the tail, including the black tip, is short and lies flat on the tail. In subadults and adults the hair on the terminal part of the tail is as long as that on the basal part, and the tail appears to be of uniform diameter all the way out to the end.

In the western subspecies of M. frenata, and in its tropical subspecies, animals so young as to have pointed tails commonly have the underparts of the body more intensely colored than do adults. The young may have salmon-colored instead of yellowish fur on the underparts.

Otherwise, in animals that have attained approximately adult proportions—which appears to be at approximately 6 months of age in males—there are no variations which are ascribable to increasing age in the color-pattern or pelage that cause the systematist to confuse species or subspecies.

Of the several parts of the skull in juvenal animals, the braincase and width of the posterior part of the palate are most nearly of the size attained in the adult, the facial part of the skull at birth is the least developed, and the interorbital region is, in relation to its ultimate adult size, intermediate in stage of development. The permanent teeth are acquired when the animal is approximately eleven weeks old.

Four age groups, based on characters of the dentition and skull, have been recognized. They are:

Juvenile.—One or more deciduous (milk) teeth present. Birth to three months of age.

Young.—Sutures widely open between the maxillae and nasals and between the premaxillae and nasals. Three to seven and a half months of age.

Subadult.—Sutures between maxillae and nasals visible but indistinct. Seven and a half to ten months of age.

Adult.—Bones of rostrum coalesced with no traces of sutures visible to the naked eye. More than ten months old.

The skull as a whole increases in size until the animal is two-thirds of the way through the stage designated as young. After this time the width of the rostrum, as measured across the hamular processes of the lacrimals, increases until approximately a third of the way through adulthood. The interorbital breadth decreases from late subadulthood to adulthood and even in adults there appears to be a slight decrease in this part of the skull with increasing age.

The average zoölogist will readily distinguish skulls of juveniles and young from adults but usually fails to distinguish subadults from adults. Nevertheless, subadults must be distinguished from adults if geographic variation is to be measured accurately. The reason for this is that such differences in the form (not size) of the skull as result from increasing age equal and often exceed the differences of a geographic sort which serve for distinguishing subspecies that have adjoining geographic ranges. All sutures in the skull, except those between the tympanic bulla and the braincase, and those on the dorsal face of the rostrum, are obliterated while the animal is a subadult. Most kinds of mammals retain sutures throughout life or until the animals are well into adulthood. Therefore, skulls of weasels offer fewer features for estimating age than do those of most mammals and the skulls of weasels that are subadults or older are more difficult to classify accurately as to age than are the skulls of most other mammals. More reliance on shape of entire skull and less reliance on extent and shape of any individual bone is necessary in estimating the age of a weasel. Wright (1947:344) shows that the weight of the baculum (os penis) is a certain means of differentiating adults from males of lesser age. When approximately eleven months old, Mustela frenata oribasus of western Montana molts from the white winter coat into the brown summer coat. At that time spermatogenesis starts for the first time and the weight of the baculum increases from less than 30 milligrams to more than 52 milligrams.

In the autumn and early winter, most of the specimens are subadults. Ordinarily the few adults obtained in these seasons can easily be segregated from the subadults because ontogenetic development in the twelve additional months of life of each of the older animals has obliterated the sutures on the rostrum, heightened (vertically) and lengthened (anteriorly) the sagittal crest, widened the rostrum, and produced still other changes in form that are revealed by direct comparison of specimens of the two ages.

Secondary Sexual Variation

The secondary sexual variation, which has been detected, is in size of the animal, relative length of the tail and shape of the skull. The female is the smaller. In the small Mustela rixosa and apparently in Mustela africana the secondary sexual difference in size is relatively slight. In Mustela frenata and Mustela erminea, males are approximately twice as heavy as females, the degree of difference very definitely depending upon the subspecies. For example, in M. e. richardsonii the recorded weights are 175 and 69 grams as opposed to 81 and 54 grams in M. e. cicognanii. In general, within one species the greatest difference in size of males and females is in those subspecies in which the animals are of large size. The secondary sexual variation in size is much more than the individual variation in either sex. The same is not true of secondary sexual difference in length of the tail (relative to the length of the head and body), which in eighteen subspecies of M. erminea is from 1 to 7 per cent longer in males than in females. In two subspecies, M. e. haidarum and M. e. olympica, the tail is a fraction of a per cent the longer in females if we may rely upon the few specimens for which collectors' measurements are available.

In both M. erminea and M. frenata the skull of the female is approximately 45 per cent lighter than that of the male, or put in the opposite way, the skull of the male is 83 per cent heavier than the skull of the female. The difference in this respect varies greatly depending on the subspecies. For example, the skull of the male is 127 per cent heavier than that of the female in M. e. richardsonii but only 33 per cent heavier in M. e. anguinae. In Mustela frenata, the subspecies noveboracensis shows most sexual dimorphism in weight of skull (3.6 and 1.7 grams) and olivacea the least (5.3 and 3.8 grams). In general, the difference in this respect is less in subspecies the individuals of which are of small size.

Therefore, as might be expected, the secondary sexual variation in weight of the skull is less in M. rixosa, individuals of which are of small size, than in M. erminea or than in M. frenata, in general of larger size. Nevertheless, in M. africana, in which the individuals are of large size, there appears to be less sexual dimorphism in weight of the skull than in M. frenata or than in M. erminea, although it should be remarked that there are too few data for M. africana to allow of forming a trustworthy conclusion concerning the amount of secondary sexual variation in that species.

The secondary sexual variation in shape of the skull consists of a slenderness in the female. In relation to the basilar length the spread of the zygomatic arches is more in males and, except in the one subspecies M. f. altifrontalis, the rostrum is broader. Also the interorbital region is relatively broader in males of most subspecies. In most subspecies of both M. frenata and M. erminea the tympanic bullae are relatively (to the basilar length) longer in females. The maximum sexual dimorphism occurs in M. erminea arctica and the minimum dimorphism in M. e. haidarum, M. e. anguinae and M. e. muricus. Taking into account all of the subspecies of each of the North American species, the shape of the skull differs most in M. erminea and least in M. frenata. In the latter species the greatest difference in shape of the skull, as was true also of its weight, is in the subspecies M. f. noveboracensis. In these two subspecies, M. f. noveboracensis and M. e. arctica, in addition to the secondary sexual variation already mentioned in the skull, females have the braincase smoother and more rounded, the postorbital-, mastoid-, and lacrimal-processes relatively smaller, and the ventral face of the tympanic bulla at its anterior margin more nearly flush with the floor of the braincase.

In the weasels, subgenus Mustela, the disparity in size of the two sexes is almost or quite as much as in any other fissiped carnivore. It is because of this large degree of difference that the skulls of the two sexes are described separately in the following systematic accounts. The need for such treatment was recognized by Reinhold Hensel (1881:127) more than sixty years ago when he wrote in the introduction to his "Craniologische Studien," of Mustela, as follows: ". . . die Geschlechtsdifferenzen am Schädel vieler Säugethiere . . . so gross sind, dass man diese wie Schädel verschiedener species behandeln muss, während in anderen Ordnungen (Rosores, Edentaten) die Schädel solche Unterschiede nichtzeigen." In the past, failure to appreciate the large amount of secondary sexual variation has resulted in erroneous deductions as regards characters of certain geographic races and has been the cause of some nomenclatural confusion, as for example, in Mustela frenata macrura, where the female was named as a separate species (Mustela jelskii).

Individual Variation

Individual variation is here considered to be the variation in one species which can occur between offspring of a single pair of parents, after variation ascribable to differences in age, sex, and season is excluded. Individual variation, therefore, is a term here used in a composite sense; it includes variations which probably represent different genetic strains within certain populations and variations induced within one generation by environmental factors.

In skulls of weasels, the individual variation in size is more than it is in relative proportions. Hensel (op. cit.) has stressed that weasels, like other carnivores, produced "dwarfed" individuals more than do herbivorous mammals. I cannot vouch for the accuracy of this view, but can say that individual variation is not greater than in some other fissiped carnivores. Impressions to the contrary probably result largely from failure to recognize age-variation. When skulls of a large series from any one locality are arranged first by sex, and under each sex according to probable age on the basis of extension anteriorly of the sagittal crest and of degree of postorbital constriction, individual variation is seen to be less than a cursory examination, even of only one sex, would suggest.

Study of a large series of one age of one sex of one species from one locality shows that some parts, of the skull for example, vary more than other parts. In illustration, among 22 male topotypes of Mustela frenata washingtoni the least interorbital breadth varied 25 per cent (9.0 mm. to 12 mm.) whereas the length of the tooth-rows varied only 13.3 per cent (15.6 mm. to 18.0 mm.). In color the individual variation definitely is more in areas of intergradation between subspecies than in other areas. Details of one such instance of intergradation are given in the account of Mustela frenata spadix.

Statements to the effect that there is much individual variation in the color of weasels, were made mostly fifty years or so ago by writers who had but few specimens from widely separated localities. Where marked climatic differences exist between localities only a few miles apart, marked differences occur in coloration of the weasels from the different localities. Much of what formerly was mistaken for individual variation now proves to be geographic variation. Individual variation actually is of slight amount in comparison with that in mammals generally. Differences in size and relative proportions of parts usually are correlated with geographic differences in color. The color does fade slightly in the period between molts. Also as a result of the seasonal color change, in autumn along the upper margin of the Austral Life-zone, some individuals become white whereas others become white on only the underparts, the upper parts changing only to lighter brown. Probably it would be correct to say that this variation was a combination of seasonal and individual variation rather than either one alone.

As might be supposed, individual variation is not the same in all species or subspecies. For example, p2 is always absent in Mustela africana and always present in certain subspecies of M. frenata. In some other subspecies of M. frenata, p2 is absent approximately as often as present. In the writer's experience, when only a few specimens are available for comparison, individual variation is more difficult to distinguish from specific and subspecific (geographic) variation than is age-variation or secondary sexual variation.

Among the larger series of specimens examined, only one instance of what might be called a mutation in the old sense of a large, sudden change, was detected. That was the loss of the second lower molar in many (less than a third) of the specimens from Newfoundland. The six instances of abnormal coloration described on pages 41 to 43, might be regarded as mutations of large magnitude but no evidence was found of repetition of an abnormality in any one population. Otherwise, in every instance where plotted, the manifestations of a variation arranged themselves about the mean in such a way as to form a smooth, unimodal curve.

Seasonal Variation

When subspecific and specific variations are the objectives of study, seasonal variation must be understood, in order to be excluded from consideration, in the same way that variations ascribable to age, sex and individualism must be understood in order to be excluded from consideration. In weasels, change in color of the pelage is the seasonal variation most important for the systematist to understand. Other seasonal variations in the pelage are hairiness versus nakedness of the pads of the feet, length of the pelage on the body, and possibly the density of the pelage on the body. In the northern half of North America, roughly speaking, seasonal change in color is so pronounced (white in winter and brown in summer) as to be easily recognized. South of this area, in the Austral and Sonoran life-zones, the color of the winter pelage differs only slightly from that of the summer pelage. In these more southern latitudes the winter pelage in almost all subspecies is of lighter color than the summer pelage and has a smoky suffusion. With material of the two seasons in hand for comparison, close attention to the variation will permit the systematist to recognize the difference in shade of brown as seasonal variation and not geographic or specific variation. Farther south still, in the Tropical Life-zone, seasonal difference in color was not detected in the material studied. Seasonal change in color is discussed in the section immediately following.

Variation in Coloration and Molt

In all American weasels (subgenus Mustela) the color, at least in summer, is brown with more or less white or whitish on the underparts. In one species, Mustela africana, there is a longitudinal stripe of brown on the middle of the light-colored underparts; this stripe is absent in each of the other three American species. Two species, M. erminea and M. frenata, always have a black tip on the tail. Of the other two species, M. africana lacks the black tip and M. rixosa may or may not have a few black hairs in the tip of its tail. White or light yellowish facial markings occur in subspecies of M. frenata from the southwestern United Stated to Central America. Subspecies having the most extensive light-colored facial markings have the remainder of the upper part of the head black. In weasels without light facial markings the upper parts of the head all are brown. In the two species, M. erminea and M. frenata, the extent to which the light color of the underparts extends down the insides of the legs and out on the underside of the tail, or the absence of light color on these parts, is a matter of geographic variation. The same can be said for M. rixosa except that first its tail is unicolored and second individual variation as well as geographic variation accounts for the color pattern on the underparts and legs in animals from the southeastern part of the range of the species.

The most remarkable feature of the coloration of weasels is the winter whitening. This occurs in the northern part of North America in each of the three species of weasels found on that continent. The black tip of the tail in M. erminea and M. frenata remains black in winter. If an individual of M. rixosa has black hairs on the tip of its tail in summer, there are thought to be black hairs there also in winter. Otherwise the winter pelage is all white in northern areas in each of the three species. In this white winter coat the animal is known as ermine.

The underlying cause seems to be protective coloration. At any rate, weasels are always white in winter if they are from areas where snow lies on the ground all winter, every winter, or almost every winter; and they are always brown if from areas where there is never, or rarely, snow in winter. The changes in color are effected by molt, one in autumn and one in spring. Animals that are brown in winter undergo the same two molts as do those that are white in winter. The capacity to acquire a white coat or a brown coat in winter is an hereditary matter just as one man grows red hair and another grows black hair. In the weasels, however, all individuals in the north turn white in winter and if one that was born there is kept through successive winters in the warmer south where there is no snow, he will still turn white each winter. A weasel born in a southern area, where all are brown in winter, molts into a brown (not white) winter coat even when kept in a cold, snowy, northern area where native weasels of the same species all turn white. Obviously, therefore, neither snow nor temperature is an immediate cause and, as we have said, the color in winter is a matter of heredity. The time of the molt, we now know, is determined by the amount of light. When nights grow longer and days shorter, a point is reached at which the lesser light received through the eyes causes the pituitary gland to cease producing a gonadotropic hormone. Directly or indirectly, the lack of this hormone stimulates molt and, probably enzyme action, or the lack of it, causes the melanoblasts of the cells in the hair follicle to be without pigment. Hence the hair grown from a follicle under such conditions lacks pigment (melanin) and is white. In spring, as the days grow longer and the nights shorter, the increasing amount of light received day by day through the eyes stimulates the pituitary gland to produce the gonadotropic hormone which directly or indirectly, stimulates molt and, probably by enzyme action, the melanoblasts are caused to be present in cells of the hair follicle and the melanoblasts provide granules of melanin pigment which are incorporated in cells of the growing hair. These granules of pigment give the hair its color.

Evidence in support of this hypothesis is given below.

Along the Pacific Coast from British Columbia southward, M. erminea (see fig. 25 on page 95) is brown in winter. This is an area where snow rarely falls and the temperature in winter ordinarily is above freezing. In the remaining part of the American range of this species the temperature in winter is below freezing much of the time and snow remains throughout the winter or for long periods. In this colder part of the animal's range, only white coats occur in winter. M. frenata likewise has a white coat in winter in the part of its geographic range where snow and freezing temperatures prevail throughout most of the winter and a brown coat in warmer, snowless areas to the southward and along the Pacific Coast. The third species, M. rixosa, exhibits a corresponding correlation between coat color and climate. On the Asiatic continent, several species, including M. erminea, provide parallel correlations and nowhere are there any exceptions for the subgenus Mustela. These data are an important part of the material on which we have based the induction that the underlying cause of seasonal change in color is a need for protective coloration.

As regards molt, most naturalists who have written upon the subject regard it as responsible for the change from the white winter coat to the brown summer coat. However, the change from brown summer coat to white winter coat has been thought by several writers to be effected by change in coloration of the individual hairs. Among those holding this opinion there may be cited Bell (1874:197) in reference to Mustela erminea, and Coues (1877:123) in reference to American specimens to which he applied the same name. More lately Hadwen (1929) has taken this same view, and Gunn (1932) also discusses the possibility of the hairs changing color. Bachman (1839:228-232), Macgillivary (1843?:158), Audubon and Bachman (1851 (vol. 2):62), Schwalbe (1893:538), Pearson et al. (1913:447), Miller (1930, 1931A), Hamilton (1933:300) and Rothschild (1942), among others, have been inclined to the opinion, or positively affirm, that the color change in autumn is the result of a molt. The papers cited above contain, in turn, references to many other printed accounts dealing with this question.

To my mind, it has not so far been demonstrated that the change in color of weasels in autumn is accomplished without a molt. Also so far as I am aware, no explanation has been given of how the pigment may disappear from the hair of weasels. Metchnikoff's (1901:156) idea that the senile whitening of the hair in man is accomplished by phagocytes which remove the pigment granules would hardly seem to explain the relatively sudden and complete autumnal change occurring in weasels. Anyhow, Danforth (1925:108), and some other students have thought that the action of these phagocytes was at most a factor of slight importance in the whitening of hair. Whatever be the complete answer to the question of how the weasel changes color in autumn, at least one specimen of long-tailed weasel, which is in process of color change in autumn, presents clear evidence of molt of the overhairs. This specimen of M. f. longicauda is no. 188408, U. S. Nat. Mus., taken on November 12, 1897, at Rapid City, South Dakota. Other specimens of M. erminea which were taken in autumn similarly show molt to be in progress. For these and other reasons, I am inclined to the opinion that the autumnal change in color, like the one in spring, is effected by molt. During the period of the autumnal color change, Noback (1935:27) had a captive M. f. noveboracensis and, each morning, found clumps of brown hair on the floor of its cage; this was strong indication that molt was responsible for the color change in this instance.

However, I freely admit that the evidence does not prove that the change from brown to white can be accomplished only by molt; in the present state of knowledge it would be unscientific to deny that the change were possible of accomplishment by other means. Also, it is true that the fifteen specimens before me of Mustela frenata, subspecies included, in process of change from brown to white, with the exception of the one from Rapid City, South Dakota, if taken individually, do not, in macroscopic examination, show definite molt lines or other absolutely convincing evidence of molt. However, these same specimens, insofar as examined microscopically, do show overhairs all white, or overhairs pigmented throughout. The lighter color of the proximal parts of the overhairs in itself should not be accepted as evidence of color change, for in the fresh summer pelage, the same condition exists. Also, careful macroscopic examination suffices to show that in the transitional pelage of autumn, the brown overhairs generally are longer than the intermixed white overhairs.

Whether the underfur behaves in exactly the same way as the overhair, I have not myself definitely ascertained, but I assume that the underfur is molted twice each year, at least in the northern populations of Mustela frenata and in the other species of more northern distribution. Schwalbe's (1893) work, including sectioning of the skin and study of the hair follicles, led him to conclude that the underfur was molted twice each year in Mustela erminea.

In Mustela frenata noveboracensis, M. f. nevadensis, and M. f. nigriauris, measurements taken on adult males show the overhairs to be longer in the winter pelage than in the summer pelage of specimens from the same locality. For example, in M. f. nigriauris from Berkeley, California, the overhairs of the summer coat (July and August) average 8 millimeters in length on the hinder back and 7 mm. on the belly, but average 9.5 mm. and 8 mm. respectively in January-taken specimens possessing the full winter coat. At Ann Arbor, Michigan, in the summer coat, the longest hairs on the hinder back average approximately 12 mm., and those on the belly, 9.5 mm., against 13 mm. and 9.5 mm. respectively in winter. Although general observations initially led me to believe that the black, terminal hairs of the tip of the tail are longer in the winter pelage than in the summer pelage, actual measurements fail to show a difference in length.

The change from one coat to the other in the long-tailed weasel has been described among others by Miller (1930, 1931A), Hamilton (1933) and Glover (1942) on the basis of captive specimens. In a general way, the progress of the molt in their specimens agrees with that which I have been able to make out from examination of skins taken in the wild. There is, however, this difference: Their specimens show a more spotted pattern when in process of hair-change than do specimens taken in the wild. Probably the more or less unnatural conditions under which these captive animals lived modified the normal progress of molt.

In wild-taken specimens of the species Mustela frenata, subspecies included, the spring molt begins on the mid-dorsal line and proceeds laterally, producing, at almost any given time, a relatively sharp molt line separating the white winter hair from the incoming brown summer coat. However, in autumn the change takes place first on the belly, then on the sides, and finally makes its appearance over all the upper parts at about the same time, with the result that the upper parts have a salt-and-pepper appearance without at this time any sharply defined molt lines. In general, the molt pattern can be said to be reversed in the two seasons; in spring, it begins on the back and in autumn, on the belly. The difference in spring and autumn color pattern is better illustrated on plate 39 than by additional description. Swanson and Fryklund (1935:123) have observed that the "spring molt proceeds differently" than the fall one in Mustela rixosa, and Barrett-Hamilton (1903:309) in commenting on the European hare (and the stoat?) remarks, "In spring the moult, and with it the brown colour, progresses in exactly the opposite order . . ." as compared with the white color of autumn, which that particular writer thought resulted from removal of pigment from the hairs rather than from molt.

The tail, excepting the black tip, lags in the molt in many instances, with the result that, especially in spring, it may retain a few white hairs as late as does the belly. In autumn it is less tardy and so far as I have observed, becomes white at about the same time that the general area of the back changes color. On the tail, the black tip itself, as clearly shown in more than a score of specimens, is molted at approximately the same time in autumn as is the pelage of the body. However, the long black hairs, which appear in, say, November, appear to increase in length until January. In spring, the long black hairs of the tip of the tail seem not to be shed at the same time as the rest of the winter pelage, but remain approximately six weeks longer and then are replaced by long black hairs of the summer coat. At any rate, this is the picture presented by a half dozen specimens of M. f. nevadensis and M. f. longicauda which do show a spring molt to be in progress on the black tip of the tail. Schwalbe similarly (1893:536-537) has suggested that the black tip of the tail in Mustela erminea in spring is not molted until about two months after the pelage on the rest of the body is changed. Schwalbe (loc. cit.) thinks also that in M. erminea studied by him, the black tip of the tail in autumn is replaced approximately one month in advance of the pelage on the rest of the body. As indicated above, my specimens of Mustela frenata, subspecies longicauda and nevadensis, do not show this discrepancy in autumn. I have considered the possibility that the black tip of the tail, in some species of Mustela, is molted only once while the remainder of the coat was undergoing two molts. My inconclusive data lend but little support to this possibility.

The difference in pattern of color between specimens taken in autumn and spring is known to some fur-trappers of my acquaintance who have suggested that molt occurs in spring, whereas the individual hairs change color in autumn. Reference to plate 39 will show how gross comparisons might lead one to this erroneous explanation of the color change.

As to time of molt: In eight subspecies of Mustela frenata, namely, noveboracensis, occisor, primulina, spadix, longicauda, arizonensis, nevadensis and effera, material is available to indicate that the autumnal molt begins in October and is completed in November, and that the spring molt occurs in March or April. A condensed list of specimens providing basis for this statement is as follows:

M. f. noveboracensis: 26 specimens in transitional pelage taken in autumn and 14 taken in spring; M. f. occisor: One topotype has acquired one-fifth of the winter pelage on October 22, 1896; M. f. primulina: 2 in November, one in March, and 2 in April are in process of change; M. f. spadix: 6 autumnal specimens and one in April show pelage change; M. f. longicauda: 7 autumnal specimens and one in April show pelage change; M. f. arizonensis: 12 specimens in autumn and 3 in spring are in process of molt; M. f. effera: One November-taken male has acquired four-fifths of the winter coat and another taken on April 21 at Fort Rock, Oregon, is half finished with the spring molt.

It may be added that no marked difference in time of either autumnal or spring molt is apparent as between the more northern and more southern localities from which the mentioned specimens come. With more complete material I would expect to find a difference in this regard.

The material of the other, more southern, subspecies of Mustela frenata has not been adequate to show the time of molting or the number of molts which occur in one year.

Animals in the northern part of the range of Mustela frenata acquire a white winter coat, whereas those in the southern part acquire a brown winter coat, and in an intervening area the winter coat may be either brown or white. By plotting on a map the localities of capture of all specimens examined in the winter coat, it was possible to outline this intervening area as shown in figure 10 on page 37. However, Dearborn (1932:36) shows that in Michigan some animals have a brown coat in winter at places farther north than figure 10 shows to be the case. Hamilton's (1933-306) map for New York shows the same to be true in that state. Accordingly, the boundaries of the area shown in figure 10, in which both brown and white long-tailed weasels occur in winter, are known to be only approximate; with full information available the belt would be represented as wider.

Fig. 10. Map showing the region (in black) where both the brown and white winter pelage is found in the long-tailed weasel, Mustela frenata.

Hamilton (1933:302) has pointed out that "Where half of the weasels remain brown, these brown winter specimens are always males." The results of my own examination of specimens not studied by Hamilton, in a general way provide confirmatory data. More exactly, my examination reveals that at the most northern localities where brown specimens occur, only males are in this coat. In explanation, it may be said that in plotting on a map localities of capture of specimens in the winter coat, thirteen places were found where both sexes were represented and where both brown and white winter coats were found. With the two sexes, it is theoretically possible to have nine different combinations of coat color. With males all brown, there might occur females (1) all brown, (2) all white, or (3) some brown and some white. In addition to these three combinations, we might have three more by finding the mentioned types of female coat color repeated where all males are white, and three more, or nine in all, by substituting a population of males some of which were brown and some of which were white. Seven of these possible combinations actually were found. The two combinations not found were all white males with all brown females, and all white males with females both brown and white. In the three instances where the males all were brown and the females all were white, the localities of capture were in the northern part of the variable area. This indicates that where the brown winter coat occurs at northern localities, the brown individuals are all males. Farther south, of course, the females, too, acquire the brown winter coat.

Stated in another way, there is a broad belt across North America from the Atlantic to the Pacific in which males of Mustela frenata at any one locality may be either brown or white in winter. Inside this broad belt there is a narrower one, approximately half as wide, in which females at any one locality may be either brown or white.

In support of the idea that color of the winter coat is an hereditary matter and that it is not dependent on temperature, the following evidence derived from my transplanting specimens of Mustela frenata supports the idea that color of the winter pelage is dependent on heredity and not on temperature or snowfall.

A male captured on June 24, 1937, in the brown summer coat in Salt Lake City, Utah, was received by me at Berkeley, California, five days later and kept in captivity almost six months. On November 17, 1937, half the pelage was white and on December 27, 1937, when next examined, the animal was in the full, white, winter coat as it was on January 25, 1938, when it died. Native weasels all turn white in winter in Salt Lake City, but in Berkeley native weasels always are brown in winter.

A juvenile or young animal, a male, captured in May, 1936, at Lafayette, Contra Costa County, California, was kept there until August 13, 1936, when transferred to Calneva at the north end of Lake Tahoe, California. The weasel was kept at Calneva until its death on December 23, 1937. In both the winter of 1936-'37 and in that of 1937-'38, the winter coat was brown as in animals from its place of origin (Contra Costa County) and unlike weasels of the Tahoe region nearly all of which turn white in winter.

Two females, each approximately two months old, captured on May 1, 1936, at James Landing, 4 miles northwest of San Pablo, Contra Costa County, California, were kept in Berkeley, California, until August 13, 1936, when they were transferred to the mouth of Blackwood Creek, on the west side of Lake Tahoe, California. On October 25, 1936, both weasels escaped. On December 25, 1936, the headless body of one of these was found approximately 300 yards south of the mouth of Blackwood Creek. The animal had been dead at most a few days when found and was in the brown winter coat. At the place of its origin all weasels are brown in winter but at the mouth of Blackwood Creek only 2 of 60 weasels caught there in the winter coat were brown; the other 58 were white. The headless weasel was identified, as one of the two formerly in captivity, by means of certain short toes, the ends of which had been clipped off when the animal was a captive. No trace of the second female was found.

A female of unknown age, in white winter pelage, captured 4 miles southeast of Tahoe City, California, and kept there until April 3, 1937, on which date it was brought to Berkeley, California, molted to brown in the spring. The first signs of the brown coat were noted on April 14. On May 24 or 25 she gave birth to 4 young which lived less than ten days. In the following winter this animal acquired a white coat. As previously noted, weasels native to the Berkeley area, where this female was kept, have brown coats in winter.

The weasels were in every instance kept in cages out-of-doors. The sides of the cages were open to the elements. A nest box in each cage provided shelter. All were of the species Mustela frenata.

The significant results, it seemed to me, were that the winter coat was the kind found in the area where the weasel originated instead of the kind found in weasels native to the areas in which the specimens were held in captivity.

That the time of molt is determined by the amount of light has clearly been shown by Bissonnette (1944:223) for American weasels of the two species Mustela erminea and M. frenata. In his words (op. cit.:246) "Reducing the daily periods of light induced molting and regrowth of new fur. . . . In the Bonaparte weasels [Mustela erminea], white replaced brown. . . . Increasing daily light-periods caused molting and change to dark brown. . . . Incomplete molts in both directions (toward white or toward brown) were produced as a result of early reversal of increase or decrease of daily light-time. . . . That this stimulus is received through the eyes and acts through the anterior pituitary gland is indicated by Bissonnette's [1935:159] studies on ferrets, a nearly related animal. That the thyroids and sex-glands are not essential is at least suggested . . . by Lyman's (1942) study on the varying hare [Lepus americanus]." It can be added that Lyman (1943:451) demonstrated in Lepus americanus that the effect of light is received through the eyes. He demonstrated this by masking the animals. To Wright (1942B:109) who studied the two American weasels, M. erminea and M. frenata, it seemed likely that the pituitary produced or released gonadotropic hormone at about the time of the spring molt and that this molt and the spring changes in the reproductive tracts of the weasels might be caused by a stimulus from a common source. Later, Wright (1950:130) injected a gonadotropic hormone into long-tailed weasels which had recently acquired their white winter pelage and thereby caused them to lose the white pelage and acquire the brown pelage. It is Lyman (1943:450) who says, in relation to Lepus americanus, "When in the physiologically white condition, the melanoblasts of the regenerating guard- and pile-hair follicles contain no melanin-forming enzyme (dopa-oxidase), which may be the reason for the lack of pigment." Schwalbe (1893) by sectioning the skin and microscopically examining the hair-follicles of M. erminea learned that the basal cells producing hairs lacked pigment granules in autumn when the European ermine (M. erminea) was acquiring its white winter coat and that the cells contained granules of pigment in spring when, as we know, the granules are incorporated in the growing hair and give it its color.

The above material, then, is basis for the account on pages 31 and 32 of what causes the weasel of northern areas to have a white coat in winter. The discerning student will instantly perceive that although some parts of the account on pages 31 and 32 are precisely accurate, other parts are the result of inferences which need to be proved. More careful work of the kind that Schwalbe (1893) and Wright (1942B) did is needed. The account on pages 31 and 32 is merely the best that can be given with the information now available.

Many writers have commented on the yellowish color, sometimes with a greenish tinge, found on the fur of weasels in the white winter coat. The stain is more often found on the tail and hinder-parts of the body than elsewhere. Possibly, partly on this account, some have ascribed this color to the smearing of the fur with urine. Still others have thought it resulted from the smearing of the fur with secretions from the anal scent glands. Schumacher (1928) takes this point of view, and while it may be that he has not proved his point, still his conclusions fit the known facts and seem sound to me. Schumacher points out that the same soiling of the fur is present in summer as well as in winter, but that on the summer pelage the stain can be detected only on the light-colored underparts. It is from this point of view that he criticizes the systematic worth of white versus yellowish-white underparts in the summer pelage of geographic races of Mustela erminea and Mustela nivalis. Although in the long-tailed weasels (Mustela frenata) the underparts of all the races are pigmented with some form of red, orange or yellow, it seems probable to me that the additional color resulting from the soiling effect of this glandular secretion explains the greater variation, found at a single locality, in the color of underparts than of upper parts in the summer pelage.

I have neither seen nor heard of a black weasel in any part of the New World or of the Old World. I have found only one albino among American specimens. It is an adult female, no. 121424, American Museum of Natural History, of Mustela erminea richardsonii, taken on August 30, 1935, at Hot Springs, Northwest Territory. This place, I am told by G. G. Goodwin who obtained the animal, is on the "Nahanni River where the rugged mountain ridges rise abruptly from the low mud flat lands, latitude 61, longitude 125." The shortness and coarseness of the hair corresponds to that of the summer pelage and not winter pelage. The pelage is everywhere white, even the tip of the tail. True, all except the nape and top and sides of the head has a faint yellowish-green tinge which has been supposed to result from staining by secretion of the anal scent glands but there is no pigment in the hair as in erythristic specimens. From the Old World, Farurick (1873:17) has recorded what he regards as an albino of Mustela vulgaris since it had no black hairs on the tip of its tail. Flintoff (1935:228, 229) records what may have been an albino Mustela vulgaris from Yorkshire and an albino M. erminea from an unstated locality. Jäckel (1873:459) mentions specimens of Mustela erminea and Mustela vulgaris, which were partly "albinistic" or "erythristic." Among the American specimens of M. erminea I have not recorded any which appeared to be either partly or wholly erythristic or only partly albinistic. Among the 1550 skins of M. frenata which were in summer pelage or brown winter pelage, five, described below, show marked abnormalities in color.

Two of these five are partly albinistic. One is an adult male, no. 223880, U. S. Nat. Mus., from Billy's Island, Okefinokee Swamp, Georgia, which has the nose as well as the area between the eyes white. Also there is a tuft of white hairs at the anterodorsal margin of each ear, scattering white hairs suggesting a postorbital bar on each side of the head, and a patch of white hairs on the mid-dorsal line behind the ears. Markings of this kind are not abnormal in M. f. peninsulae, the subspecies adjoining on the south, except for the white nose which clearly is an instance of partial albinism. The second specimen is a subadult male, of M. f. noveboracensis, no. 177679, U. S. Nat. Mus., in process of acquiring the brown winter coat, taken on November 27, 1911, at Gaylordsville, Connecticut. It has white markings on the nose, on the right side of the neck, on the right hind foot and right forefoot, and on the tip of the tail. The white area of the nose on the left side extends back to the eye, but on the right side barely encircles the nose-pad. On the right side of the neck, all that area between the foreleg and ear is white from the mid-dorsal line (including 7 or 8 millimeters to the left of the mid-dorsal line) down to the throat, which is white as it is also in normal individuals. The toes of the right hind foot are more extensively white than in normal specimens of noveboracensis, and all of the right forefoot as well as the wrist is white. The tail is of striking appearance because of its tricolor pattern. The proximal part is of the normal brown color. The black terminal part commences proximally at the usual place, but the distal 11 millimeters of the fleshy part of the tail bear only pure white hairs producing a terminal white pencil 35 millimeters long.

The three other specimens abnormally colored are erythristic individuals. An adult male of M. f. latirostra, no. 7574, coll. D. R. Dickey, taken on April 14, 1918, at Covina, Los Angeles County, California, has the color of the upper parts greatly restricted, and, in addition, has spots and blotches of the color of the underparts distributed over the back and rump. A spot of this same color occurs above each ear. Incidentally, this and other subspecies of Mustela frenata from the Pacific Coast of North America obviously have the factor for erythrism operating over a larger part of the body than it does in M. erminea or than in M. f. noveboracensis, where the underparts sometimes are white. In M. f. latirostra and in other subspecies from the Pacific Coast the light color of the underparts always is tinged with this reddish color.

Another erythristic specimen is a young male of M. f. nevadensis, no. 23493, U. S. Nat. Mus., taken on August 6, 1890, at Birch Creek, Idaho. It has all of each foreleg, the axillary regions, and a saddle-shaped area over the shoulders of the same buff-yellow color as the underparts.

The third erythristic specimen is a subadult female, of M. f. oregonensis, no. 47149, Mus. Vert. Zoöl., taken on December 20, 1930, at Carlotta, Humboldt County, California. This specimen appears to be white and initially was thought to be merely an individual in the white winter coat. Closer examination, however, shows that it has a light wash of ochraceous or faint reddish color. Also, other specimens taken in winter at Carlotta show that weasels there do not acquire a white winter coat. The only normally brown area is approximately three millimeters in diameter at the anterodorsal margin of the pinna of the right ear. The tip of the tail is black as in a normal specimen. The specimen in question is actually pure white only on top of the head from a short distance behind the ears on over the forehead nearly to the eyes, and on the inside of the ears. In a normally colored animal this area is the dark area of the head. In this freak, the other parts of the head, which, in individuals of normal coloration are the white or light orange facial markings, have the reddish cast of the remainder of the body, although the color is less intense than on the back. The collector noted that the specimen had eyes of normal color. A possible explanation for the coloration of this specimen is that this species has three factors for color, one for the black tail tip, one for the reddish color, and a third, missing in the specimen in question, for the blackish brown.

For some more exact knowledge concerning this erythristic type of coloration, we are indebted to Pitt (1921:99), who describes a population of polecats, Mustela putorius, in Cardiganshire, England, in which this erythristic variation is maintained in a state of nature. In ferrets, Mustela furo, Pitt (op. cit.:114) notes that ". . . erythrism is certainly dependent on a Mendelian factor, being dominant to albinism and recessive to the black-brown coloration. Both in the ferret and polecat, erythrism seems to be correlated with increased size, and certainly in the ferret is usually accompanied by a quick temper and general increase in vitality."

Variations of Taxonomic Worth

Variations of taxonomic worth usually are referred to as characters. For example, shortness of the tympanic bulla is a character, and the opposite condition, long tympanic bulla, is another character. Specific variations, that is to say specific characters, are provided by the color-pattern, length of tail, number of premolar teeth, shape of the tympanic bullae, and length of the braincase in relation to the length of the tooth-bearing parts of the skull. Subspecific characters are provided by color-pattern, color itself, size as measured by weight of the animal, and its linear measurements, size of the skull, and size and shape of parts of the skull. The characters distinguishing subspecies from one another are not of a different nature from those distinguishing species from one another.

Given any one of the above structural features, say, dorsal outline of the skull, several characters may be provided by it. For example, weasels of the species Mustela frenata have the dorsal outline of the skull convex in southern Louisiana, straight in Missouri and concave in North Dakota, thus providing three characters. This is geographic variation. These variations, characters in zoölogical parlance, when plotted on maps, reveal the geographic occurrence of, say, the convex shape of the skull. In combination with other characters, for example, dark color and short tail, basis is provided for recognizing a subspecies, in this instance Mustela frenata arthuri of Louisiana. Because the change from convex to flat skull takes place geographically at about the same place (in eastern Texas) as does the change from short tail to long tail, and the change from dark color to light color, it is easy to draw a line there marking the western geographic limit of occurrence of the M. f. arthuri. This same line marks also the eastern margin of the geographic range of the subspecies Mustela frenata frenata, the subspecies next adjacent to the westward. On this line and for several miles to either side of it weasels show varying combinations of these three characters or an intermediate condition as regards one or more of the characters, or both. For example, from a locality in eastern Texas a weasel may have (1) a facial pattern exactly intermediate between that of the unicolored face of arthuri and that of the bicolored face of frenata, (2) the long tail of frenata and (3) the convex skull of arthuri. In the sum of its characters this specimen is exactly intermediate between typical arthuri and typical frenata. Another specimen from the same place may differ from the first specimen only in having the tail slightly shorter. The total "score" for the two specimens is, therefore, by a very slight margin in favor of arthuri. Let us suppose that we obtain a third specimen from the same place and that it has the face marked like that of arthuri but the tail fully as long, and the skull as lacking in dorsal convexity, as in frenata. Now the score is definitely for frenata. For convenience of handling, the population is referred to frenata, providing that the average of specimens from a nearby locality to the westward is not in favor of arthuri. In event the average of specimens from a locality next adjacent to the westward is in favor of M. f. arthuri, the total evidence from the two localities may be weighed together and appropriate decision as to subspecific status of weasels from the area is made according to what the average is for the area as a whole.

The three individual animals of an intermediate sort are ordinarily termed intergrades. This implies that their characters are the result of mixed parentage—perhaps a female of M. f. arthuri and a male of M. f. frenata but probably each parent itself was an intergrade and the offspring, of which we examined three, owe their characters to reproductive processes operating in obedience to Mendelian laws of inheritance.

The two kinds of animals, Mustela frenata arthuri and Mustela frenata frenata, are identified as subspecies because of the intergradation between them. If at this and all other places where the geographic ranges of arthuri and frenata met there was no crossbreeding (no intergrades), the two kinds would be treated as distinct species. Intergradation, and the lack of it, are accepted as the criteria of subspecies and species, respectively.

These criteria suffice for animals, in this instance weasels, which have a continuous geographic distribution. Some kinds of weasels are confined to islands, as for example the islands off the coast of Alaska and British Columbia. Because weasels are land animals, crossbreeding in nature between the weasels of two islands is, of course, impossible. A modified test (used in the study here reported upon) in deciding on specific versus subspecific status in these instances can be made as follows: On the adjacent mainland, ascertain the degree of difference between two subspecies whose geographic ranges meet (for example, M. e. richardsonii and M. e. alascensis). Next ascertain the degree of difference between the insular kind of animal and the kind on the mainland. If the degree of difference is greater when the insular kind is compared than when only the kinds of the mainland are compared, the insular kind is to be regarded as a species. If the degree of difference is no greater between the insular kind and the mainland kind than it is between the two adjacent mainland kinds, the insular kind is to be regarded as a subspecies. In short, for insular kinds, the criterion is degree of difference, with the limitation of geographic adjacency, rather than intergradation.

The geographic variation (subspecific characters) found could be spoken of as two kinds: First, there is the variation which is expressed in a general trend for a long distance, producing, in general, a cline of even slope; and second, that of inconstant trend in any one direction. In his "The Rabbits of North America" Nelson (1909:34-35) has commented on the latter type of variation as follows: "While studying series of specimens from all parts of the vast range occupied by the geographic races of such species as Sylvilagus floridanus and S. auduboni, I have been impressed with evidences of fluctuation of both external and skull characters. These fluctuations are somewhat wavelike in character and rise to central points of extreme development and then sink away to intermediate borders beyond which new waves rise. Where the waves of differentiation are pronounced they mark recognizable geographic races. Within the area covered by the larger or geographically broader waves of differentiation (recognized as of subspecific value), smaller waves of differentiation are included, which may represent local variations in intensity of characters of the subspecies, or these characters may diminish and the variation tend in other directions, sometimes even closely reproducing the characters of another subspecies occupying a distinct area." In Mustela frenata, much of the geographic variation at first inspection appears to be of this nature. Closer scrutiny, however, reveals that the repetition, at geographic intervals, of several features of color and structure are closely correlated with environmental features which are repeated only at these same places.

In Mustela erminea, much of the variation is of the first kind, namely, that which can be expressed as long clines of relatively even slope. As several authors have said, zoölogical classification based on this kind of variation is like dividing the spectrum and depends largely upon the standards set, for, theoretically, the possibilities of subdivision are unlimited. Actually, however, none of the clines has an even slope and the possibilities for subdivision therefore are limited. Also, when several features are used, instead of only one feature, the classification is more satisfactory even if the basis is more complex.

Some features of structure which provide subspecific characters are mentioned below.

Total length, of males, ranges from 598 to 360 mm. in M. frenata and from 336 to 228 mm. in M. erminea. There is no cline of sustained slope in M. frenata but in M. erminea there is a progressive decrease in total length from north to south.

Length of tail varies from as little as a half to as much as seven-tenths of the length of the head and body in M. frenata, the subspecies neomexicana having the long tail and the two subspecies arthuri and primulina having short tails. The geographic ranges of primulina and neomexicana are contiguous. In M. erminea there is likewise no variation of a clinal nature in length of tail and furthermore the variation is much less than in M. frenata.

In length of hind foot, which in males varies from 49 mm. in northern populations of M. erminea to 28 mm. in southern populations, the same cline is seen as in the total length of animals of this species. In M. frenata, however, there are several decreases and increases along any straight line which can be drawn through the geographic range of the species. The range of variation in males is 41 mm. (M. f. arizonensis) to 59 mm. (M. f. macrophonius).

Weight of the entire animal is an excellent measure of size but weights are unavailable for many subspecies. In M. frenata, the two subspecies texensis and macrophonius probably are the heaviest and effera, arizonensis and helleri probably are the lightest. Geographically the variation in weight behaves in approximately the same way as does the measurement of total length. In M. erminea the variation in weight of males is from 206 grams in northern animals to 58 grams in southernmost populations, there being a relatively constant gradient geographically.

Degree of hairiness of the foot-soles in M. frenata clearly is linked with the temperature; in regions of high average temperature the hairiness is least and in regions of low average temperature it is most. The decrease in hairiness is accomplished in two ways, namely, smaller breadth and decreased length of individual hairs and decrease in number of hairs on a given area of dermal surface. This correlation holds throughout the entire north to south range of the species. Corresponding differences are found on the same latitude where topographic diversity in an east to west direction produces northern conditions at high altitudes and southern conditions at low altitudes. The conclusion seems unavoidable that climate, directly or indirectly, determines the degree of hairiness. Less careful observations were made on the hairiness of the soles of the feet in other species but it is clear that the northern species M. erminea has the most hair on the foot-soles and that M. africana, the tropical weasel, has the least. In this regard, M. frenata is intermediate as it is also in geographic position.

Figs. 11-15. Dorsal views of adult skulls of each sex of five subspecies of the ermine, Mustela erminea, to show secondary sexual variation and geographic variation in size of the skull. Males on the left and females on the right. All × 1.

Note especially the geographic variation in decreasing size of the skull from north to south in each sex, and that the secondary sexual variation in size of skull is less in ermines with small skulls than in those with large skulls.

Fig. 16. Map showing the localities where the skulls, represented in figures 11-15, were obtained.

The maximum length of facial and carpal vibrissae is attained in M. erminea in the far north. In weasels from north of the Arctic Circle the longest facial vibrissae extend posteriorly beyond the posterior border of the ear. In the tropical weasel, M. africana, the facial vibrissae do not extend posteriorly beyond the ear and the carpal vibrissae are not so long as the distance between their bases and the apical pad of the first digit. The correlation of long vibrissae with low temperature, is mentioned here merely because length and density of pelage were under consideration.

The most obvious and most exact correlation between change in climate and change in the animal is furnished by color. This is well shown in the one species, Mustela frenata, to which the following remarks apply unless indication is given to the contrary. The color of the upper parts varies from bay (blackish brown) in M. f. panamensis to buckthorn brown (light brown) in M. f. neomexicana. The color of the head varies from solid brown (white chin excepted) to contrasting black and white markings.

Dark color of the upper parts is associated with a large area of this color; the enlargement of this area is at the expense of the area of light color on the underparts. In the weasels of darkest color the upper parts occupy four-fifths of the circumference of the body (as measured in the anterior lumbar region) but in the lightest-colored weasels the upper parts comprise only two-thirds of the total circumference. In these light-colored animals the color of the underparts extends onto the underside of the tail and down the insides of the legs and over the feet whereas in the animals with the darkest upper parts the entire tail, feet, and legs below the knees ordinarily are of the same dark color as the upper parts. The length of the black tip on the tail varies inversely with the length of the tail, probably because the lightest-colored weasel has the longest tail. In some subspecies the black brush is almost half as long as the tail-vertebrae but in others is less than a fourth as long as the tail-vertebrae.

The extent of the color of the head, as well as the intensity of the color there, varies markedly and is correlated with climatic conditions. The extent and intensity of this dark color is greater in weasels inhabiting regions of heavy rainfall than in those inhabiting regions of sparse rainfall. Considering the geographic range of each subspecies of Mustela frenata, that of M. f. panamensis has the maximum of rainfall. Reference to the colored plate (1) will show that in M. f. panamensis (2) the black of the head is extended over all of the upper parts. M. f. macrura (1) of Perú, to the southward, is from an area of lesser rainfall and is correspondingly lighter colored. Returning to panamensis (2) as a starting point and proceeding northward to the range of nicaraguae (3), which also has lesser rainfall, thence another step northward to Guatemala, which has still less rainfall, the weasel there, M. f. goldmani (4) has the black extending posteriorly only to the shoulders. M. f. leucoparia (5) from Michoacán, and M. f. frenata (6) from Tamaulipas are from progressively more northern and also progressively drier regions. In M. f. frenata (6) the dark color extends posteriorly only to the ears and is blackish rather than black. In M. f. neomexicana (7) of the extremely arid parts of Durango, Arizona, and New Mexico the dark marking of the head is confined to a brown spot on the nose. Its geographic range is the most arid of those of all of the subspecies. The contrast between neomexicana (7) and panamensis (2) illustrates the great range of geographic variation in color which occurs in the one species. Continuing from the geographic range of neomexicana (specimen from Safford, Arizona) northwesterly 480 miles to Riverside, California (see 8, latirostra), 430 miles north to Point Reyes, California (see 9, munda), and finally 570 miles north to Tillamook, Oregon (see 10, altifrontalis), each place with more rainfall than the one farther south, another correlation of increasingly dark coloration with increasing amount of rainfall is illustrated.

This geographic variation, it should be remembered, is all within one species. It is the more significant still when we remember that the same correlation, with never an exception, occurs at hundreds of places within the geographic range of the species. A particular feature of climate, namely rainfall, and possibly therefore humidity, is concerned in this correlation. The same correlation, heavy rainfall and dark color, is shown also in the other species of North American weasels. The conclusion is unavoidable that climate, directly or indirectly, determines or influences the color of weasels.

The light facial markings appear in American weasels in two separate geographic areas. One is the southwestern United States, México and northern Central America. The second area is in the same latitude, in Florida and adjoining parts of Georgia and Alabama. In the western weasels the markings are white south of latitude 32° N. North of this latitude, the facial markings, if at all extensive, usually are of the same yellowish color as the underparts of the body. Weasels of southern California and its interior valley usually have these yellowish instead of white facial markings. The light facial markings, in this instance, white markings, attain their maximum extent in M. f. leucoparia of the southwestern margin of the tableland of México, at latitude 19° N. A gradual decrease in area of the light facial markings occurs both to the north and south; they disappear at 10° N in M. f. costaricensis and at 35° N at approximately the southern limits of range of M. f. arizonensis and M. f. nevadensis. In the mild climate of California the light (yellowish) facial markings are found at still higher latitudes. These light facial markings crop up as vestiginal remnants, consisting of a few white hairs, in some individuals of nearly all races of weasels.

In certain parts of the skull there are trends, in size and shape, which continue for long distances geographically. In other words, clines can be recognized. Changes in size and shape in some other parts of the skull are wavelike; change toward narrower rostrum, for example, is not progressive in a given geographic direction for any great distance. Length of the upper tooth-rows and zygomatic breadth, when expressed as percentages of the basilar length, and also the actual length of individual teeth vary geographically in the same wavelike fashion as does the width of the rostrum.

Size of the skull, on the other hand, shows a sustained trend for a long distance; it becomes progressively smaller from the southern United States southward to Columbia, South America. This clinal variation can be demonstrated by plotting on a graph, the basilar length, the zygomatic breadth, or the weight of the skull. Beginning at Mérida, Venezuela, and proceeding southward to increasing elevations in the mountains of South America, there is a reversal of the direction of the variation in this cline; weight of skull, for example, increases to the southward from Mérida for a considerable distance. A cline of decreasing width of the postorbital constriction of the skull is evident from Panamá north into Texas.

Variations in the tympanic bullae provide many characters useful in distinguishing weasels from different localities. Most of these characters have to do with degree of inflation of the bullae. Indirectly correlated with degree of inflation is first the extent of removal of the anterior margin of the bulla from the glenoid fossa and foramen ovale, and second the form (convex, flat, or concave) of the part of the squamosal bone between the foramen ovale and the anterior margin of the tympanic bulla. As one proceeds southward from, say, southwestern Kansas through the geographic range of the species Mustela frenata, there is a progressive deflation of the bulla, an increase in length of the space between its anterior margin and the foramen ovale, and the floor of the braincase in front of the bulla changes from ventrally concave to ventrally convex. (See figs. e and h of pl. 24 and figs. e and f of pl. 27.)

One extreme of this variation in bulla is shown in Mustela frenata neomexicana (fig. e of pl. 24), in which the anterior margin of the bulla (viewed from the ventral side) rises vertically from the floor of the braincase to form a 90-degree angle. The other extreme, the uninflated bulla, is in Mustela frenata panamensis (fig. e of pl. 27), in which the anterior margin of the bulla is not raised above the floor of the braincase. This variation is remarkable because it occurs within a single species. Otherwise, in the family Mustelidae, differences in the tympanic bullae as great as that between the two subspecies M. f. neomexicana and M. f. panamensis, occur only between genera. The need for caution in inferring the limits of variation for a particular structure in one species or genus, on the basis of variation in another group, is therefore obvious.

Speaking now of full species, the most inflated tympanic bullae in American weasels are in Mustela frenata, and more restrictedly in those subspecies of it which occur in the temperate region. Subspecies of M. frenata in Central and South America, as already noted, have less inflated bullae. The tropical weasel, Mustela africana, of the Amazon drainage of South America has the bullae still less inflated (see fig. i of pl. 39 and fig. f of pl. 40). The bullae are less inflated even than in the mink, subgenus Lutreola. In M. africana the cleidomastoideus, omotrachelian, levator scapulae, and rhomboideus profundus muscles take origin from a fossa on the mastoid bone, whereas in the forms with greatly inflated bullae these muscles take origin from a raised ridge or tubercle. Using Mustela frenata of the temperate region as a starting point and proceeding northward, a reduction in inflation of the tympanic bulla is seen also in that direction in that Mustela erminea has less inflated bullae. The bullae are less inflated in southern than in far northern (arctic) populations of Mustela erminea. In erminea the lesser inflation is real enough but at the same time there appears to be less inflation than actually exists, for the squamosal floor of the braincase is "pushed down." This places the anterior end of the tympanic bulla farther in the braincase than it otherwise would be. Although the anterior end of the bulla is flattened to the extent that it resembles the sharp edge of a splitting-wedge, inspection of the lateral and medial edges shows that in its central part the bulla is more inflated than it is in the weasels of Central and South America.

For reasons set forth later, M. erminea is judged to resemble the ancestral stem form more closely than does any one of the other three American species of weasels. If this judgment is correct, the shape of the tympanic bullae of the American weasels may be explained as follows: In the subspecies of Mustela frenata of the temperate regions of North America the bullae have most nearly been pushed out of the braincase and at the same time have undergone some enlargement. The subspecies of this same species in Central and South America represent an earlier stage in the evolution of American weasels and retain less inflated bullae—less inflated even than those of the southern subspecies of erminea. M. africana probably separated from the stem form at a still earlier time if we may judge by the lesser inflation of its tympanic bullae. There are other reasons for thinking that africana separated from the stem form earlier than M. frenata did. During the time that elapsed since the separation of M. frenata from the stem form, the tympanic bullae of M. erminea probably increased slightly in size, as probably also did the brain but without shoving the auditory complex forward from its former position.

DISTRIBUTION AND SPECIATION

Weasels of the subgenus Mustela are known from the Pleistocene but not from deposits laid down at an earlier time (see page 10). The Pleistocene weasels from Rancho La Brea of southern California and from Potter Creek Cave and Samwel Cave, both of northern California, are subspecifically indistinguishable from the weasels living in those same localities today. The other notable occurrence of weasels in the Pleistocene is in the Conard Fissure of Arkansas. Brown (1908:181, 182, pl. 17) names two kinds from the Fissure. One is an extinct subspecies (Mustela frenata gracilis) possibly of the species which occurs in the same region today and the other, Mustela erminea? angustidens, is an extinct subspecies of a species which occurs only farther north today. M. erminea came south, probably in front of one of the ice sheets, as did several other species of American mammals, now of more northern distribution, that left their remains in Conard Fissure. Mustela rixosa is not recorded as a fossil in America although it is known from the "Diluvial" deposits of the Old World; see Woldrich (1884:1000), who employs the name "Foetorius minutus n. sp.," and see also Zimmerman (1943:295-296).

The ermine, Mustela erminea, is the most generalized of the full species. For example, the number of teeth is as large as in any other species and greater than in certain species. The teeth are sharp-pointed, uncrowded, and individually less specialized than in any other American weasel. M1 has the inner half, or lobe, of approximately the same size as the outer lobe instead of much larger than the outer lobe (the outer lobe is the larger in several other species). The tympanic bullae are less inflated and less protruded from the braincase. The skull is rounded, and has no marked crests and ridges whereas the skulls of the other species are more pronouncedly modeled and sculptured. Therefore, it is possible to think of these other species as derived from M. erminea. A derivation in the reverse direction would be more difficult. From the foot soles of an ermine, or a weasel closely resembling an ermine, the more complex soles of Mustela africana could have been derived by a decrease in hairiness, although it would be necessary to suppose that the thenar pad has been retained in africana and has been lost in the living erminea. The alternate possibility, namely, that the thenar pad was a relatively recent acquisition in the africana line seems less probable. The tail of erminea is of "average" length and in size of entire animal erminea is intermediate between the other American weasels. Structurally, Mustela erminea appears to be nearest the stem form from which all of the living weasels ascended. Its present holarctic distribution is in harmony with the view that it is a direct descendant from the stem form because the stem forms of most of the known kinds of mustelids appear to have lived in the holarctic region. To be sure, Mustela erminea is regarded as having undergone some progressive change in structure, but less than the other weasels, in the period of time when the weasels were evolving from the stem form.

The least weasel, Mustela rixosa, seems to be an ancient type and to judge from the size and proportions of its parts, was differentiated from the erminea stem at a time earlier than were the other American Recent species of weasels. In size, in reduction of the tail, and in proportions of the skull, M. rixosa is, in each instance, the most aberrant of all the weasels, Mustela nivalis of Europe and western Asia included. This aberrancy results from the retention of certain primitive features, in the teeth and basicranial region, and from specialization in proportions of the skull. The skull is long, deep, and narrow. These proportions probably are adaptations permitting the animal to follow the smaller kinds of mice into their burrows. In most of that part of North America where erminea and rixosa occur together, erminea is a much larger animal and takes as prey almost all kinds of land vertebrates that it is powerful enough to kill. These include varying hares and ptarmigans. The least weasel, rixosa, can hardly manage such large prey and lives on the smaller rodents. Mustela rixosa may eat numbers of insects (see page 176 beyond),—a kind of food which Mustela erminea is not known to eat. Apparently the two species are able to live in the same areas because each eats a somewhat different kind of food than does the other and hence they do not compete to the point where one is crowded out by the other. This is the case in the latitudes where the two species of weasels are of different bodily size, but in the southernmost latitudes where these two species occur, erminea becomes almost as small as rixosa and only one of the species, to the exclusion of the other, occurs in a given area. All through the Rocky Mountains, south of Montana and in the territory west of these mountains all the way to the Pacific Coast, only the small subspecies of erminea is to be found. In the Alleghenies of the eastern United States only rixosa occurs. In New England where erminea approaches the size of rixosa, the latter is unknown. Probably this exclusiveness results from competition for food, although competition for dens, safe breeding places and other requirements of life may be involved.

The species erminea invaded the western United States and in the process of invasion probably developed there the small size appropriate to permit erminea to live in that latitude before it could do the same thing in the Appalachian region. Later than erminea, the least weasel, Mustela rixosa, which was small to begin with, also spread southward from the holarctic region, stopped short in the western United States at the northern boundary of the area in which erminea was of small size, but in the Appalachian region of the eastern United States continued on southward to the limits of temperature tolerant for it because erminea had not yet penetrated into that region and no other small carnivore was there to offer competition.

The long-tailed weasel, Mustela frenata, occurs mostly south of the regions inhabited by the ermine, and mostly south of the region inhabited by the least weasel which appears to live as well with frenata as with erminea. It is true that erminea and frenata occur in the same region, but this is a relatively narrow belt across the United States; and from within it a person cannot go far either north or south without reaching a region in which only one of the two species occurs. Exception has to be made for the Rocky Mountains and the Sierra Nevada, where erminea is of exceptionally small size. In these mountains and in the boreal mountainous parts of the intervening region of the United States, erminea and the large-sized frenata occur together over a wide area. Presumably the two occupy different ecologic niches, much as rixosa and frenata probably do where they occur together.

Most of the geographic range of the long-tailed weasel, M. frenata, is in the temperate region. Structurally, this species is the most advanced of the American weasels. Its dentition is the most highly specialized for cutting. M1 is relatively small and the inner lobe is slightly larger than the outer lobe. The skull, throughout, is more modeled than in the other species; the rostrum, the lower jaws and the teeth—all parts of the offensive equipment—are well developed relative to the corresponding structures in other weasels; the basicranial region exhibits an advanced stage of development in that the tympanic bullae show the maximum degree of inflation. Also, they are thrust far out of the braincase, thereby providing more room for the relatively larger brain which is protected by a more solidly built braincase than in erminea.

Several subspecies of Mustela frenata occur in the tropics, that is to say, south of the Mexican tableland and on the coastal plain to the east of it. Each is structurally more primitive than subspecies of the temperate region. As compared with Mustela frenata frenata of the temperate Mexican tableland the size in these tropical subspecies is smaller; the tail is shorter; the braincase and entire skull are less modeled; the postorbital breadth is more; the teeth are smaller; the deuterocone of P4 is not so far anterior to the protocone; the tympanic bullae are less inflated, are farther removed from the foramen ovale, and a larger proportion of each bulla is contained within the braincase. These features serve to set off from northern races of frenata all those subspecies of frenata which occur from southern México southward to the northern and western limits of the Amazon drainage of South America. The Amazon Basin is inhabited by another species, Mustela africana, having more primitive characters.

In the species frenata, the explanation for this abrupt change in characters between the animals of the temperate highlands and those of the tropical lowlands may be this: In the early Pleistocene, after the emergence of much or all of Central America took place, weasels distributed themselves over the Isthmus and into South America. These weasels were more generalized in structure than those now inhabiting the uplands of México. Failure of this stock of weasels often to cross some still-persisting water barrier, or failure of this stock to cross some water barrier that was widened or reformed because of a rise in sea level in some one of the interglacial periods of the Pleistocene cut the frenata stock into two or more parts. After the land connection was established or re-established and when the necessary precedent plants and rodents again had established themselves, the two groups of weasels, one from the northern tableland of México, and the other from the southern area of tropical complexion, met. The weasels of the frenata stock that reinvaded the area from the north probably did so by following along the chain of high volcanic cones and narrow uplifts. If and when a subsequent inundation occurred in some part of Central America, weasels were stranded on the adjacent mountains—converted into islands—only the higher parts of which were above water. Mustela frenata costaricensis and Mustela frenata goldmani may be examples of a northern stock of weasel that pushed southward in the highlands and became stranded for a short time. Following the latest emergence of land to provide a continuous highway between the two continents, weasels from the south and the insular populations, as for example, M. f. costaricensis, were the first to invade the low tropical areas most recently under water. When the Pleistocene history of Central America is better known, the facts will provide a useful means of testing the hypothesis that has been outlined immediately above.

As explained above, fossil specimens of M. frenata from deposits of the last half of Pleistocene time show that no appreciable change occurred in some areas, for example, in the vicinity of Hawver Cave and Samwel Cave of California, and that but slight change occurred in other areas, for example, in southern California (fossils from Rancho La Brea) and probably in the central United States (fossil from Conard Fissure). It is possible to imagine, therefore, that the two groups of weasels, one occurring southward only as far as the highlands of Central America and the other occurring in northern South America, had not differentiated sufficiently in the period of their isolation to prevent crossbreeding when they last came into contact. If the separation of the two groups had been maintained for a longer period, the two groups, tropical weasels and austral weasels, probably would have been so different when the two met as to prevent crossbreeding and they would have constituted two full species instead of only one.

Mustela africana is the most primitive of the American weasels. Some of the most important structural features that mark it as such are in the basicranial region. The tympanic bullae are less inflated than in other weasels, are pointed anteriorly and posteriorly, and do not have the lateral margins carried outward to the outer margins of the braincase. The mastoid sinus is not involved, by inflation or marked modification in the production of the auditory complex. Between the alisphenoid and the squamosal there is a clear demarcation posteriorly from a point directly lateral to the foramen ovale. This demarcation permits a transverse rounding of the alisphenoid to form a longitudinal ridge between the anterior margin of each bulla and the base of the pterygoid of the same side. Nevertheless, there is no such specialization of this primitive, structural feature such as occurs in some African and Asiatic mustelids in which the tympano-pterygoid part of the alisphenoid fuses with the tip of the hamulus of the pterygoid. However, the tympano-pterygoid eminence has not been obliterated in M. africana as it has in the other American weasels. Another primitive feature in the basicranial region of M. africana is the tendency toward separation of the paroccipital processes from the tympanic bullae. The thenar pad of the foot probably is an inheritance from a primitive ancestor since the pad is present in the viverrids and in a majority of mustelids judged to be more primitive than Mustela.

Some specializations are obvious in Mustela africana. One is the reduction in number of premolars; p2 is absent whereas it is normally present in the other weasels; P2 has one instead of two roots; and, in relation to the other teeth, m2 is smaller. The shortness of the preorbital part of the skull in relation to the length of the skull as a whole may reflect the mentioned reduction of the premolars or retention of a primitive shape of skull, or both. Also, certain features which denote immaturity in other weasels are retained in adults of this species, as for example, sutures on the dorsal face of the preorbital region of the skull.

Figs. 17-22. Views of the feet of American weasels (subgenus Mustela) to show differences in number and arrangement of the pads and variation in degree of hairiness of the soles. × 1-1/2. In each figure, left-forefoot on left, and left hind foot on right.

Fig. 17. M. rixosa rixosa, Halifax, N.S.; juv., ♀, 7425 U.S.N.M.

Fig. 18. M. erminea richardsonii, Ft. Chimo; ad. ♀, 14866 U.S.N.M.

Fig. 19. M. frenata noveboracensis, Mich., July 7, 1913; ad. ♂, 44689 M.Z.

Fig. 20. M. f. frenata, Brownsville, June 1, 1892; yg. ♂, 34043 U.S.N.M.

Fig. 21. M. frenata panamensis, Panamá, February 17, 1911; sad. ♀, type.

Fig. 22. M. a. africana, Pará, Brazil, Sept., 1908; yg. ♂, 37475 A.M.N.H.

Figs. 17, 18 and 19. Drawn from specimens preserved in alcohol.

Figs. 20, 21 and 22. Drawn from relaxed feet of dried skins.

Mustela africana, all characters considered, is the most aberrant of the American weasels. That is to say, greater difference prevails between M. africana and any other American weasel than exists between any other two American weasels. The distinctive cranial and dental characters, excepting the reduction in number of premolars, are of a primitive nature. For example, the relatively wide postorbital region, the large braincase that is inflated anteriorly, and the flattened tympanic bullae are points of resemblance to the holarctic Mustela erminea, the species which is regarded as most closely resembling the stem form. Also, the mentioned characters in adults of M. africana resemble ontogenic stages passed through by other weasels. Consequently, it is thought that M. africana crossed the filter-barrier from North America to South America, remained isolated from the original stock for a length of time sufficient to permit africana to differentiate from North American weasels and vice versa to such a degree that crossbreeding with the frenata stock was prevented when frenata, at a later time, pushed southward over the, then zoölogically less-effective, water barrier, or continental bridge if it was by this time in existence.

Fig. 23. Diagram indicating probable relationships of the species of American weasels.

The four full species of American weasels may well be thought of as having the same stem form of which erminea is the most nearly direct descendant. Geographic and climatic changes may have operated to isolate, and then to foster morphologic differentiation of, first rixosa in Eurasia, next africana, third the tropicalis section of M. frenata, and finally M. frenata itself, leaving M. erminea as a modern version, somewhat altered to be sure, of the stem form. Some of these ideas are expressed in figure 16. The climate is different in the ranges of the several species and the climate has changed through time in the ranges of at least many subspecies. Natural selection of morphological features best adapted to a particular kind of climate probably has altered some species more than others. M. erminea in almost every one of its characteristics is generalized and potentially progressive whereas africana retains more characters which are truly primitive along with a few which are specializations. M. africana is potentially the least progressive of any of the American weasels. The most specialized weasels are the North American races of Mustela frenata. A progressive series of increasing specialization is comprised in (1) M. africana, (2) the M. tropicalis (Central American, lowland) section of M. frenata, and (3) the races of M. frenata in North America.

Considering now features of the environment which have obviously influenced the distribution and speciation of weasels, water barriers are important. Bering Strait, Carquinez Strait (along with San Francisco Bay) which opens through the Golden Gate, and the channels between the islands of southeastern Alaska, have contributed to the formation of subspecies. The difference is really slight on the two sides of Bering Strait and San Francisco Bay and is slightly more on two sides of each of several of the channels between the islands of southeastern Alaska. The differences between the weasels on the two sides of one of these water barriers supposedly result from the preservation in animals on one side, or on one island, of small mutations, which would be swamped by crossbreeding if the water barrier were not present. The effect of this isolation is easily seen if ermines from the Queen Charlotte Islands are compared with those of the opposite mainland. The degree of morphological difference is great. Isolationwise, the Queen Charlotte Islands are the seaward end of a chain, beginning with Admiralty Island in southeastern Alaska, and are farther from the mainland, zoölogically, than the distance in actual miles across the water channel would suggest. Between any two islands that are geographically consecutive, however, and between the mainland and the first island of the chain, the difference in the ermines is small. In other places, water barriers of equal or greater width have contributed little if anything to the differentiation from one another of weasels on the two sides of the water barrier. The strait between eastern Canada and Newfoundland is an example.

The absence of water, or scarcity of it to a degree that closely approaches absence, in any large area appears to prevent weasels from living there. At any rate, the one sizeable region of North America from which weasels are unknown is the desert of the southwestern United States and adjoining part of northwestern México. More precisely, in western Arizona, the Mohave Desert and the desert of northwestern Sonora, collectors of mammals have repeatedly sought small carnivores without ever finding any weasels.

Degree of moisture is closely correlated with color in weasels. Humidity and cloudiness as well as actual precipitation seem to be involved. Even if we take into account average annual rainfall alone, the darkest-colored weasels are found in the areas of heaviest rainfall and the lightest-colored weasels in areas of lightest rainfall (extreme type of desert where no weasels occur being excepted). In any large region where there is a geographic gradient in rainfall, the transition from light to dark color almost exactly parallels the increase in amount of rainfall. Within a given species the same color reappears in widely separated areas that have the same amount and seasonal distribution of rainfall. This correlation is repeated so often that one can almost certainly say that heavy rainfall, or the associated phenomena of high humidity and cloudiness, acting separately or together, causes an increase in intensity of color. Relative extent of the color of the upper parts and underparts and presence and absence of light facial markings seem also to be correlated, in a more general way, with differences in rainfall. A fuller discussion of the nature and amount of the variation in color is given on page 51.

Temperature seems not to be an important factor in directly limiting the distribution of weasels, since M. frenata occurs from the hottest to some of the coldest parts of the Americas. Do M. erminea and M. rixosa range no farther south, than they do at present, because high temperatures constitute a barrier? No evidence is known to me which provides an answer, one way or the other, to this question. Granting that temperature is unimportant in limiting the distribution of weasels, it seems to cause geographic variation. Increase in mean annual temperature is correlated with decreased size in M. erminea and with increased size in M. rixosa. Temperature, it seems, causes the hair to vary; the pelage is harsher and sparser in weasels from tropical regions than in those from boreal regions. Difference in number of hairs is especially well shown on the soles of the feet. In the weasels from the far north, the pads are concealed by hair and in the weasels from the tropical regions the soles are mostly bare. Also, the hair on the soles of the feet is longer in northern than in southern weasels. Furthermore there is seasonal change in length of the hair on the soles of the feet; at a given locality in southern Canada the hair of the white winter coat is so long on the soles of the feet as to obscure completely the palmar and plantar pads whereas the hair of the brown summer coat is shorter and leaves these pads boldly exposed to view. This seasonal change, as would be expected, is most marked in animals of northern regions and is not perceptible in those from the tropics; it is correlated with increase in seasonal change as the distance from the equator increases.

Temperature and moisture acting together may cause extensive white facial markings, that neither alone would cause. In Mustela frenata these markings occur where there is heavy rainfall and high mean annual temperature. Where there is heavy rainfall and a low mean annual temperature they do not occur and where there is high mean annual temperature and light rainfall the markings are not pure white but are of the same color as the underparts. Plate 1 and the description of color on page 51 may be consulted in this connection. Extremely high mean annual temperature together with extremely heavy rainfall may inhibit the development of light facial markings. M. f. meridana, panamensis and costaricensis are cases in point. In either direction, north or south, from the territory inhabited by these three subspecies a similar combination of temperature and rainfall is found and similar light facial markings appear there.

Considering the delicate response of structure to climate, a person naturally questions whether or not natural selection accounts for all of the differences between subspecies. To show that natural selection determines the color of Mustela frenata, it would be necessary to assume that climate, color, and utility of color are positively correlated. Although climate (rainfall) and color are correlated in such a manner that three subspecies of weasel in places as far apart as New England, Perú, and the state of Washington are colored alike, other features of the three environments are unlike. Kinds of animals which the weasel catches for food, and flora in which the weasel finds concealment, are dissimiliar. If natural selection alone determined the color, some difference in color would be expected between the weasel which needed to be obliteratively colored, that is camouflaged, the better to catch a Phyllotis in Perú and the weasel in Washington which needed nature's aid in catching Microtus. Mustela frenata goldmani of the highlands of southern México, which is known to attack the huge pocket gophers, Orthogeomys and Cratogeomys, has a weaker dental armature than Mustela frenata texensis which does not have to overcome prey so formidable as does goldmani. Equally formidable enemies endanger M. f. goldmani and texensis. Examples of this nature could be multiplied. Without actually proving anything concerning selection, these examples give reason for us to suppose that some characters are not determined by natural selection.

Another question upon which data obtained from a study of Mustela has some bearing, is this: Where the geographic ranges of two subspecies meet, why does not the swamping effect of crossbreeding cause one subspecies to disappear? Although swamping may have occurred in some instances, it does not occur in the majority of instances. Witness the long-continued existence of the living subspecies Mustela frenata nevadensis of which skulls are available from Pleistocene deposits. Therefore, its distinctive characters, cranially at least, have been maintained for a long time. Furthermore, these characters are maintained over a large geographic region more than a thousand miles across. On the eastern margin of its range, at the eastern base of the Rocky Mountains in Colorado, M. f. nevadensis intergrades in a relatively narrow belt with the lighter-colored, longer-tailed and cranially different Mustela frenata longicauda, which has a geographic range almost equally extensive. M. f. longicauda also is uniform in its characters over a large area but at approximately 400 miles east of the base of the Rocky Mountains, it begins to intergrade with the darker-colored, shorter-tailed and cranially different Mustela frenata primulina and does so over a belt of 100 miles or more in width. At any given locality within this wide belt of intergradation the range of individual variation ordinarily does not exceed that in animals from a given locality well within the geographic range of M. f. longicauda. In the narrow belt of intergradation along the eastern base of the Rocky Mountains, the range of individual variation at several places is greater than in animals from a given locality well within the geographic range of M. f. longicauda or for that matter from well within the geographic range of M. f. nevadensis.

Considering the dominance and recessiveness of genes and the genetic mechanism in general by which characteristics of offspring are inherited from their parents, it would seem that M. f. longicauda and for that matter M. f. nevadensis and M. f. primulina would lose their distinctive characteristics because of the crossbreeding that is every year going on between longicauda and nevadensis on the one hand and between longicauda and primulina on the other hand.

Sumner (1932:84) suggests that homogeneity is prevented by population pressure. Applying his suggestion to the species Mustela frenata we could say that the subspecies longicauda pressing westward meets strong pressure from the subspecies nevadensis pressing eastward and that the width of the zone of intergradation between the two subspecies varies inversely with the strength of the population pressure from the two sides. Sumner recognizes that according to his hypothesis the two contiguous races would remain distinct only so long as there was a preponderance of centrifugal movement from both of the centers of dispersal. Sumner (op. cit.:85) recognizes that an abrupt change of environmental conditions could account in part for the boundaries of the ranges of the two subspecies and finally that his hypothesis does not certainly answer the question of why crossbreeding does not result in homogeneity between two subspecies with contiguous geographic ranges.

The hypothesis of harmoniously stabilized complexes of genes was offered by Timofeeff-Ressovsky (1940:124) to explain why the swamping effect of crossbreeding does not obliterate subspecies. The hypothesis takes into account that any one of several characters of a subspecies may be caused by several genes. Some characters of this kind may be favored by natural selection more than others. In the belt of intergradation between two subspecies, where two of these favored characters meet, a "biological tension" as Huxley (1939:415) terms it "will result, which will produce partial discontinuity between the two groups. Each group will evolve a gene-complex which is not only broadly adapted to the external environment of the central area of its range, but is also harmoniously stabilized, in adaptation to the internal genetic environment, by the selection of modifiers." Crosses, that is to say intergrades, between the two subspecies will lack this stabilization and will therefore be at a selective disadvantage. The zone of intergradation will therefore remain narrow; intermediates are constantly being brought into existence there by crossing but are as constantly being extinguished by selection.

These two hypotheses are the best that geneticists yet have offered. Neither has been tested and both, as originally proposed, would hardly apply everywhere because there are some contradictions.

I can offer no better explanation—in fact no original one as good—but would emphasize that under similar climate, weasels remain constant in character, or at most do not vary beyond certain limits. Crossing at the margins of ranges of two subspecies does not result in homogeneity of weasels. There is, therefore, some stabilizing influence, or influences, that maintain, and even develop, structural characteristics of weasels in opposition to the contrary tendency of crossing.

That this influence not only maintains uniform characters over areas of large extent, but also permitted their development over large geographic areas, must logically be supposed, for otherwise, considering the swamping effect of crossing, such variations would not have made their appearance in more than a few individuals. Also, if the races had been formed in response to some kind of physiological differentiation, or other non-climatic cause, the characters of the population in the belt of intergradation probably would disappear in a short time. In any event the close correlation between degree of change in weasels and degree of change in climate, at once makes one suspect that climate has been the deciding factor. Finally, when one recalls that in certain parts of the animal, certain characters invariably appear under similar climates and never under dissimilar climates, the evidence is almost conclusive that, given long enough time, the animals vary in response to climate. The variations (characters) may be induced indirectly, but are no less exactly reproduced than if they can be shown to be induced directly.

In considering how the species and subspecies of American weasels were formed and in attempting to account for some of the individual characters, it is profitable to view the facts in the light of some of the theories of species-formation—theories that are accessory to that of organic descent and that are concerned with the modus operandi of organic descent.

In any group of closely related species some of them, by the laws of chance, are almost certain to be more primitive than others. Mustela is no exception and the more primitive species closely match, in several characters, ontogenetic stages passed through by more advanced species. Jaeckel's (1902) theory of metakinesis, therefore, is to be considered since it postulates that many cases of epistasis occur; that is to say, that many sexually adult animals are arrested in development in early otogenetic stages and undergo no further development. Although this theory is appealing upon initial consideration, it is less so when we recall that in Mustela there is a direct correlation of increasingly primitive structure with decreasing latitude as one proceeds from the steppe of North America southward to the equator. It follows that the conditions seen in Mustela can be explained even better than by metakinesis, by assuming that the several species have differentiated from a stem form at different times, have developed at different rates, have developed in different directions and that ontogeny recapitulates phylogeny.

The theory of Age and Area (see Willis, 1922) holds that the species of widest distribution are, on the average, the oldest, and that the species which are distributed over small areas are, in general, of recent origin. So far as the weasels are concerned, little support is given to this theory. The same can be said of any one of the teological theories, including the orthogenesis of post-Darwinian writers. All of these imply a determinate line of variation controlled by the inherent qualities of the organism. The idea that the several species of Mustela result from mutations of large degree and sudden appearance is contrary to the evidence accumulated. In fact the evidence rather clearly indicates that the mutations which may have occurred were of small degree and in most instances owe their preservation to natural selection.

The data obtained by the study of weasels accords almost exactly with the theory of species-forming embodied in Matthew's (1915) "Climate and Evolution." Although the essential features of this theory were made out from a study of families and orders and therefore would not be expected to apply to members of only a genus or subgenus, the facts known about the present distribution of American Mustela, nevertheless, are strikingly in accord with the ideas advanced by Matthew. In the first place, climate is an important factor in the evolution of the weasels. In the second place, the line of migration seems to have been outward from the holarctic region. In the third place, the geographic changes necessary to explain the present distribution of the species of Mustela are not extensive and do not affect the permanency of oceans as defined by the continental shelf. These three statements are, almost verbatim, those made in the first three of the five points of Matthew's (1915:172-173) thesis. The remaining two points of Matthew's thesis have to do with generalizations based on evidence obtained from sources outside the scope of the present study.

Furthermore, the relative degrees of specialization of the different species and subspecies in relation to their geographic distribution are in accord with the ideas elaborated by Matthew. For instance, the most primitive species is farthest south from the probable center of dispersal, the holarctic region. Also the full species become progressively more primitive as one proceeds southward from the holarctic, or at least from the northern half of the nearctic, region. Although, in view of the known geological changes that have occurred in the Caribbean region, we cannot say that the more primitive species owe their positions entirely to having been pushed farther south from the center of dispersal by actual and continuous contact and competition with the more advanced species, this seems to have been the case in a general way. At any rate the more primitive kinds seem to have been prevented from pushing northward by the more advanced kinds which developed there and the latter have actually pushed southward.

Additionally and in review: There is strong indication that the American species of weasels were formed by gradual and slow change. Much of this change probably is the result of natural selection operating on fortuitous variations of a minor nature, but, also, particular features of the environment, especially climate, and more especially amount of rainfall, seem to compel variations that differentiate subspecies and that characterize full species—compel some of them without the direct operation of natural selection, or at least compel them within limits so wide that natural selection exerts no exact control.

HISTORY OF CLASSIFICATION

In the earlier accounts of American weasels, from the time of Linnaeus and before, up until 1890, names then in use for European weasels frequently were applied also to those in North America. For the next 50 years, and almost without exception after 1896, the American weasels were regarded as specifically distinct from those in the Old World. In this 50-year period many new names were proposed, usually as full species, although now that material from more localities has been brought together and studied, geographic intergradation is evident between many of the named kinds and most of these names now therefore take only subspecific rank. In 1933 Glover M. Allen showed that Mustela rixosa occurred also in the Old World, and in 1943 I emphasized that a second American species, Mustela erminea, was circumpolar in distribution. In neither rixosa, nor erminea, however, were the subspecies the same in the two continents. To this general outline of the nomenclature, exception must be made for weasels of the southwestern United States, México and Central America, and South America, because as early as 1813 a distinctive name was given to one of these and weasels from the three areas mentioned were, so far as I know, never given names of Old World kinds.

The first paper that could be regarded as revisionary in nature was "Remarks on the species of the genus Mustela" by the zoölogist and world-traveler, Charles L. Bonaparte, in Charlesworth's Magazine of Natural History, for 1838. In that paper three new names, Mustela cicognanii, M. richardsonii and M. longicauda, all still valid, were proposed for American weasels.

Audubon and Bachman in their "Quadrupeds of North America," which appeared in parts from 1845 to 1853, recognized 5 species. Actually they were dealing with only 3 taxonomically valid kinds. For one of these, Mustela frenata noveboracensis, they were misled by the difference in size between males and females, and in the males by the presence of a brown coat in some and a white coat in others. The male that was white in winter they regarded as Putorius ermineus of the Old World; the male that was brown in winter they designated by their earlier proposed name P. fuscus, and the female they named P. agilis. The ermine, subspecies M. erminea cicognanii, they called P. pusillus. Their fifth name, P. frenatus, included at least some animals that today are assigned to the subspecies M. frenata frenata. Each of three and perhaps four of the five names employed by Audubon and Bachman embraced individuals of more than one species and in that sense the names were composite.

Only five years later, in 1858, Professor Spencer Fullerton Baird's great work, "The Mammals of North America," made it clear that no American weasel was identical (in the modern subspecific sense) with any Old World weasel, and he applied most of his names in a correct zoölogical sense. It is true that he thought that the female weasel of the eastern United States was specifically different from the male, misapplied to it the name richardsonii, and did not correctly allocate every one of the few poor specimens available to him of the little ermine (M. e. streatori) of the Pacific Coast; but he did recognize that the least weasel was a distinct kind and his treatment in general was excellent.

After Baird came a period of great confusion in which most writers did no better than had Audubon and Bachman, ordinarily confusing the two sexes as different species, and, in 1877 in his "Fur-bearing Animals," Elliot Coues went rather to the other extreme and allowed only 4 kinds to all of the Americas, regarding two of these, for purposes of zoölogical nomenclature, as identical with the European species.

But, in 1896 Outram Bangs published "A Review of the Weasels of Eastern North America" in which he correctly recognized eight kinds. Although some of these were treated by him as full species, whereas the material accumulated since 1896 has shown that subspecific status is in order, his names, still in use, were correctly applied in every instance, save probably one. This was his use of Putorius richardsonii for the animal now known as M. e. arctica. Unlike the earlier, excellent treatment by Baird, this accurate one by Bangs was heeded and followed by subsequent writers. For example, Dr. C. Hart Merriam in the same year, 1896, accepted Bangs' conclusions except for correcting the application of the name richardsonii. The principal contributions of Merriam's paper "Synopsis of the Weasels of North America" were first, the wider geographic scope and second, the naming as new of several kinds outside the geographic area studied by Bangs. Otherwise the work was not up to Dr. Merriam's usual standard and the internal evidence of haste in its preparation and the superficial study of some of the material at his disposal explain why the weasels of North America since that time have been but little better understood than in 1896. Baird and Bangs, then, unquestionably did the best systematic work on the American weasels.

In 1916 Dr. Joseph A. Allen published a valuable paper on the South American weasels. The material available to him was inadequate and prevented a thoroughly satisfactory treatment. There are too few specimens even today to permit of a thorough treatment of the South American weasels in the present paper; nevertheless the material today is more nearly adequate than it was in 1916 and it is hoped that the systematic arrangement is correspondingly improved.

Chronological List (annotated) of Specific and Subspecific Names Applied to American Weasels

At least eighty-seven specific and subspecific names have been proposed for American weasels. Of these sixty-nine are now regarded as valid designations of recognizable subspecies. The average is 1.2 names per subspecies. Some names in the following chronological list were a second time applied wholly or in part to some other kind of weasel. In general, mention of the second or any other later application is omitted from the following list but two usages of agilis (1844 and 1853) and of americana (1865) are recorded.

1734. javonica (Mustela) Seba, Locupletissimi Rerum naturalium Thesauri ..., 1:77, 78, pl. 48, fig. 4. The weasel to which this name was applied was said to have come from Java. Since no animal answering to the description has again been found in Java, and because specimens from Central America or possibly some from northern India, may do so, it is conceivable that Seba was the first to distinguish by name an American weasel from those in the Old World. My attempts to locate the specimen concerned in places where it might have been preserved along with some of the other specimens thought to have belonged to Seba have been fruitless. Since it is impossible positively to link Seba's description with any known weasel, no further use is made of the name javonica in the present account.

1772. erminea (Mustela) Forster [= Mustela erminea richardsonii], Philos. Trans., London, 1772:373. Forster's use of the name is one of the earliest applications of it to American animals. The name dates from Linnaeus, Syst. Naturae, (10th ed.) 1:46, 1758, with type locality in Europe. In the subspecific sense the name applies to the ermine which occurs over most of the Scandinavian Peninsula, if Miller (1912:387) be followed in regarding the type locality as Upsala, Sweden. If, instead, Cabrera (1913A:394-396) be followed in regarding the type locality as in Switzerland, the name, in the subspecific sense, will apply to the ermine of continental Europe. As the earliest available name applied to the circumpolar species concerned, it is used now as the name of the species in the New World as well as in the Old World. From the time of Forster until approximately 1890 the name erminea by many, but not by all, authors was applied to the American weasels in the belief that they were zoölogically indistinguishable from those in the Old World. From 1896 to 1943 the name was not used by American authors at all because the ermine of America was in 1896 treated nomenclaturally by Merriam as specifically distinct from the animal in the Old World. Since 1943 erminea has been used in the specific sense for American animals in recognition of the circumpolar distribution of the species. Some of the early allocations of American specimens to erminea probably resulted in a composite use of the name in that one or another subspecies of the American species Mustela frenata may also have been included with individuals truly of the species erminea.

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1772. nivalis (Mustela), Forster, Philos. Trans., London, 1772:373. This is one of the early applications of this name to American weasels of small size, made in the belief that they were taxonomically the same in America and Europe. Linnaeus, Syst. Nat. (12th ed.) 1:69, 1766 is the authority for the name [Mustela] nivalis, and the Province of Vesterbotten, Sweden, is regarded as the type locality. The name is in use today for the common weasel of Europe and parts of Asia. Animals of the species nivalis are intermediate in size between Mustela erminea and Mustela rixosa. The name as used for American animals by some authors who wrote later than Forster did, probably was composite in that these authors may have applied the name to the small weasels of North America and thus may have intended it to apply not only to Mustela erminea cicognanii but also to females of Mustela frenata noveboracensis, and conceivably to both sexes of Mustela rixosa of any American subspecies.

1813. Brasiliensis (Mustela) Sevastianoff, Mem. Acad. Imp. Sci. St. Petersburg, 4:356-363, table (= plate) 4. This name was proposed for a weasel brought to St. Petersburg by Capt. Krusenstern on his return from a voyage around the world. The animal was said to have come from Brazil, but to judge from the description, came instead from México, Central America, or west of the Andes in South America, and was based on some one of the subspecies of Mustela frenata. Although the name was in use for more than 60 years it was shown by Merriam (1896:27) to be unavailable because it was preoccupied by Mustela brasiliensis, a name earlier used by Gmelin (Syst. Nat., ed. 13, p. 93, 1788) for a South American otter.

1815. vulgaris (Mustela), Ord, Guthrie's Geography as reprinted by Rhoads in 1894, vol. 2, p. 291. This use by Ord is one of the earliest applications of this name to American weasels, in the belief that the smaller weasels of North America and Europe were zoölogically the same; [Mustela] vulgaris seems originally to have been proposed in 1777 by Erxleben on p. 471 of vol. 1 of his Syst. Regni Anim., for the weasel of the temperate part of Europe and to be a synonym of Mustela nivalis Linnaeus (1766). Probably the name as used by Ord was composite in the sense that he may have intended it to apply to females of Mustela frenata noveboracensis as well as to one or both sexes of Mustela erminea cicognanii and, if he ever saw them, to the two sexes of Mustela rixosa (one or several subspecies).

1818. africana (Mustela) Desmarest [= Mustela africana africana], Nouv. Diction. d. Hist. Nat., 19:376. In 1808 E. Geoffroy St.-Hilaire visited Portugal and was given several African primates and the specimen of Mustela named by Desmarest in 1818 who wrongly supposed that it, like most of the primates, came originally from Africa. After the name had been misapplied for 95 years Angel Cabrera showed that it pertained instead to the tropical weasel of Brazil. Of distinctive names applied to American weasels today, this is the one first proposed.

1832. frenata (Mustela) Lichtenstein [= Mustela frenata frenata], Darstellung neuer oder wenig bekannter Säugethiere, pl. 42 and corresponding text unpaged. This name is the first one available for the long-tailed weasel and therefore applies to the species as a whole.

1838. Cicognanii (Mustela) Bonaparte [= Mustela erminea cicognanii], Charlesworth's Mag. Nat. Hist., 2:38. The name erroneously spelled Cigognanii was correctly spelled on page 39. For a detailed consideration of this name see the account of the subspecies cicognanii on page 120.

1838. Richardsonii (Mustela) Bonaparte [= Mustela erminea richardsonii], Charlesworth's Mag. Nat. Hist., 2:39. Until 1896 the name sometimes was applied to the subspecies now known as M. e. arctica and sometimes to part of the subspecies now designated as M. e. cicognanii under the principal treatment of which see (page 120) for a detailed account of the basis of the name richardsonii, and the reasons for regarding Fort Franklin as the type locality.

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1838. longicauda (Mustela) Bonaparte [= Mustela frenata longicauda], Charlesworth's Mag. Nat. Hist., 2:39. The type locality appears to be Carlton House, Saskatchewan, and the name always seems to have been applied to the long-tailed weasel of the Great Plains, although in some earlier accounts the name was used in a more inclusive sense to refer also to animals now of subspecies closely allied to longicauda. As with the two preceding names, a detailed consideration of the basis for, and application of, this name is given on pages 120-123 in the account of Mustela erminea cicognanii.

1840. Noveboracensis (Putorius) Emmons [= Mustela frenata noveboracensis], Quadrupeds of Mass., p. 45. This name was credited by Emmons to De Kay who in the same year published it in his report on the "Zoology of New York" but without a description and De Kay's name is a nomen nudum. Emmons' was the first use of the name accompanied by a recognizable description and therefore the name must date from Emmons although this obviously was not his intent since he credited the name to De Kay.

1842. fuscus (Putorius) Audubon and Bachman [= Mustela frenata noveboracensis], Jour. Acad. Nat. Sci., Philadelphia, 8: (pt. 2) 288.

1842. pusilla (Mustela) De Kay [= Mustela erminea cicognanii], Nat. Hist. of New York, Zool., Pt. 1, Mammalia, p. 34. This name was proposed for small weasels of 12 to 13 inches in length of which the tail amounted to a fourth of the same and although obviously applying in considerable part to the earlier named M. e. cicognanii seems to have included some individuals of the also earlier named M. f. noveboracensis.

1843. xanthogenys (Mustela) Gray [= Mustela frenata xanthogenys], Ann. and Mag. Nat. Hist., 11:118, February, 1843, was applied to all of the long-tailed weasels of California that had light-colored facial markings. Merriam in 1896 suggested that San Diego was the type locality and in 1899 Bangs proposed the name mundus for the California weasel north of San Francisco Bay thus restricting the application of the name xanthogenys. In 1936 Hall further restricted the application of the name and applied it to the long-tailed weasel of the big interior valley of California, pointing out that the name was correctly applied to this weasel of the big interior valley or possibly instead to the race named munda.

1844. agilis (Mustela) Tschudi [= Mustela frenata agilis], Untersuch. ü. die Fauna Peruana, p. 110, is a name applied today to the race of weasel of the Temperate Zone of the western Andes and intermountain valleys of Perú.

1851. nigripes (Putorius) Audubon and Bachman [= Mustela nigripes], Quadr. N. Amer., 2:297, 1851, applies to the black-footed ferret of North America.

1853. agilis (Putorius) Audubon and Bachman [= Mustela frenata noveboracensis], Viv. Quadrupeds N. Amer., 3:184, pl. 140. This name was proposed for the female in the mistaken belief that it was specifically distinct from the larger male for which several names already were available. Also Tschudi in 1844 had already used the name Mustela agilis for a South American weasel.

1864. aureoventris (Mustela) Gray [= Mustela frenata aureoventris], Proc. Zoöl. Soc. London, 1864:55, pl. 8, February 9, 1864, is the name applicable to the dark-colored weasel of the Pacific coastal region of Ecuador and Columbia.

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1865. americana (Mustela erminea Var. 3) Gray, Proc. Zoöl. Soc. London, 1865:111. The larger individuals of American weasels of both Mustela erminea and Mustela frenata from the Atlantic Coast to as far west as Carlton House, Saskatchewan, were lumped under this name because Gray desired more information than he then had before recognizing as different from one another several species proposed for America up to the time concerned. The name is unavailable because it is preoccupied by Mustela americana Turton (1806) the name for the American marten.

1865. americana (Mustela vulgaris Var.) Gray, Proc. Zoöl. Soc. London, 1865:113. Under this name the smaller weasels of the northern and northeastern part of North America were lumped by Gray but the name is preoccupied and can be ignored.

1874. affinis (Mustela) Gray [= Mustela frenata affinis], Ann. and Mag. Nat. Hist., 14 (ser. 4):375, 1874, from New Granada [= Colombia], had the type locality restricted to Bogotá, Colombia, by Allen in 1916, and is applied to the long-tailed weasel of the tropical and temperate zones of the eastern Andes of Colombia.

1874. macrura (Mustela) Taczanowski [= Mustela frenata macrura], Proc. Zoöl. Soc. London, for 1874, p. 311, pl. 48, May 19, 1874, applies to the long-tailed weasel of central Perú and northern Ecuador.

1877. culbertsoni (Putorius) Coues [= Mustela frenata longicauda], Fur-bearing animals ..., p. 136, 1877, is based on specimens from Fort Laramie, Wyoming. In the past the name has been regarded as a nomen nudum but there is some reason for regarding it as having nomenclatural status. In either event it is here arranged as pertaining to the long-tailed weasel of the Great Plains which takes the prior name longicauda. See the account of longicauda for a more detailed account of the name culbertsoni.

1877. aequatorialis (Putorius (Gale) brasiliensis) Coues [= Mustela frenata aureoventris], Fur-bearing animals ..., p. 142. Proposed "merely as a substitute for Gray's [supposedly] preoccupied name," aureoventris.

1881. stolzmanni (Mustela) Taczanowski [= Mustela africana stolzmanni], Proc. Zoöl. Soc. London, for 1881, p. 835, November 15, 1881, is applied to the tropical weasel of the Upper Amazon Basin.

1881. jelskii (Mustela) Taczanowski [= Mustela frenata macrura], Proc. Zoöl. Soc. London, for 1881, p. 647, May 17, 1881, was proposed for the female in the mistaken opinion that it was specifically distinct from the larger male which the same author previously had named macrura.

1891. arizonensis (Putorius) Mearns [= Mustela frenata arizonensis], Bull. Amer. Mus. Nat. Hist., 3:234, June 5, 1891, until 1936 was applied to long-tailed weasels of most of the western United States west of the Great Plains but by restriction since 1936 has been applied only to the animals in parts of Arizona and New Mexico.

1894. peninsulae (Putorius) Rhoads [= Mustela frenata peninsulae], Proc. Acad. Nat. Sci. Philadelphia, 1894:152, June 19, 1894, applies to the weasel of central and southern Florida.

1896. alascensis (Putorius richardsonii) Merriam [= Mustela erminea alascensis], N. Amer. Fauna, 11:12, June 30, 1896, with type locality at Juneau, Alaska, has been used for the ermine of southeastern Alaska ever since it was proposed. In 1944 separate subspecific rank was accorded ermines on several of the islands of southeastern Alaska which proportionately restricted the range assigned to alascensis.

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1896. streatori (Putorius) Merriam [= Mustela erminea streatori], N. Amer. Fauna, 11:13, June 30, 1896, applies to the ermine of the Pacific Coast from Puget Sound, Washington, south nearly to the Golden Gate of California.

1896. arcticus (Putorius) Merriam [= Mustela erminea arctica], N. Amer. Fauna, 11:15, June 30, 1896. Ever since it was proposed, this name has been applied to the subspecies of ermine of Alaska and the northern parts of Canada.

1896. kadiacensis ([Putorius arcticus]) Merriam [= Mustela erminea kadiacensis], N. Amer. Fauna, 11:16, June 30, 1896, is a valid name applied to the ermine of Kodiak Island, Alaska.

1896. washingtoni (Putorius) Merriam [= Mustela frenata washingtoni], N. Amer. Fauna, 11:18, June 30, 1896, applies to the long-tailed weasel of the southern Cascades of Washington and the northern Cascades of Oregon.

1896. saturatus (Putorius) Merriam [= Mustela frenata saturata], N. Amer. Fauna, 11:21, June 30, 1896, was little used until 1936 but applies to long-tailed weasel of limited region in northern California and southern Oregon.

1896. alleni (Putorius) Merriam [= Mustela frenata alleni], N. Amer. Fauna, 11:24, June 30, 1896, applies to weasel of Black Hills region.

1896. oregonensis (Putorius xanthogenys) Merriam [= Mustela frenata oregonensis], N. Amer. Fauna, 11:25, June 30, 1896, applies to long-tailed weasel of parts of western Oregon and northern California.

1896. goldmani (Putorius frenatus) Merriam [= Mustela frenata goldmani], N. Amer. Fauna, 11:28, June 30, 1896, applies to the long-tailed weasel of Chiapas, and parts of Guatemala and Salvador.

1896. leucoparia (Putorius frenatus) Merriam [= Mustela frenata leucoparia], N. Amer. Fauna, 11:29, June 30, 1896, applies to the long-tailed weasel of Michoacán and Nayarit.

1896. tropicalis (Putorius) Merriam [= Mustela frenata tropicalis], N. Amer. Fauna, 11:30, June 30, 1896, applies to the long-tailed weasel of the Tropical Life-zone of Veracruz.

1896. spadix (Putorius longicaudus) Bangs [= Mustela frenata spadix], Proc. Biol. Soc. Washington, 10:8, February 25, 1896, applies to the long-tailed weasel of Minnesota and adjoining areas.

1896. rixosus (Putorius) Bangs [= Mustela rixosa rixosa], Proc. Biol. Soc. Washington, 10:21, February 25, 1896, applies to the least weasel of Saskatchewan and adjoining areas and as the first available name for the species has been used as the specific name for the species in America since 1896.

1897. paraensis (Putorius (Mustela) braziliensis) Goeldi [= Mustela africana africana], Zool. Jahrb., abt. f. systematik, geogr. u. biol., 10:560, pl. 21, September 15, 1897, a synonym for the weasel of the lower Amazon area.

1898. neomexicanus (Putorius frenatus) Barber and Cockerell [= Mustela frenata neomexicana], Proc. Acad. Nat. Sci. Philadelphia, p. 188, May 3, 1898, applies to the long-tailed weasel of New Mexico, Arizona, Durango and adjoining areas.

1898. haidarum (Putorius) Preble [= Mustela erminea haidarum], Proc. Biol. Soc. Washington, 12:169, August 10, 1898, applies to the ermine of the Queen Charlotte Islands, British Columbia.

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1899. notius (Putorius noveboracensis) Bangs [= Mustela frenata noveboracensis], Proc. New England Zoöl. Club, 1:53, June 9, 1899, was applied to the long-tailed weasel of the Carolinas until 1936 since which time it has been regarded as a synonym of noveboracensis.

1899. occisor (Putorius) Bangs [= Mustela frenata occisor], Proc. New England Zoöl. Club, 1:54, June 9, 1899, applies to the long-tailed weasel of central and northern Maine. Until 1936, occisor was ordinarily used as the name of a full species but since then has been arranged as a subspecific name under Mustela frenata.

1899. mundus (Putorius xanthogenys) Bangs [= Mustela frenata munda], Proc. New England Zoöl. Club, 1:56, June 9, 1899, is now applied, and generally has been since 1899, to the long-tailed weasel of the coastal district of California north of San Francisco Bay.

1899. muricus (Putorius (Arctogale)) Bangs [= Mustela erminea muricus], Proc. New England Zoöl. Club, 1:71, July 31, 1899, applies to the diminutive ermine, often erroneously designated least weasel, of the western United States.

1899. oribasus (Putorius (Arctogale) longicauda) Bangs [= Mustela frenata oribasus], Proc. New England Zoöl. Club, 1:81, December 27, 1899, applies to the long-tailed weasel of the Rocky Mountains northward from Yellowstone National Park.

1900. eskimo (Putorius rixosus) Stone [= Mustela rixosa eskimo], Proc. Acad. Nat. Sci. Philadelphia, 1900:44, March 24, 1900, is applied to the least weasel of Alaska and adjacent parts of boreal North America.

1901. allegheniensis (Putorius) Rhoads [= Mustela rixosa allegheniensis], Proc. Acad. Nat. Sci. Philadelphia, 1900:75, March 25, 1901, applies to the least weasel of the eastern United States.

1902. perdus (Putorius tropicalis) Merriam [= Mustela frenata perda], Proc. Biol. Soc. Washington, 15:67, March 22, 1902, applies to the long-tailed weasel of the Lower Tropical Life-zone from southern Veracruz into Guatemala.

1903. microtis (Putorius) Allen [= Mustela erminea richardsonii], Bull. Amer. Mus. Nat. Hist., 19:563, October 10, 1903, is a name applied to an individual ermine of small size from Shesley, British Columbia, which Allen thought was specifically distinct from the ermine of the Hudsonian Life-zone and adjacent territory. Now the name is arranged as a synonym of richardsonii.

1904. audax (Putorius) Barrett-Hamilton [= Mustela erminea arctica], Ann. and Mag. Nat. Hist., ser. 7, 13:392, May, 1904. In the original description the type locality, Discovery Bay, was erroneously stated to be in Greenland and the name audax until 1945 was applied to the kind of weasel occurring in northern Greenland whereas the type specimen was taken instead in northern Ellesmere Island and because the weasel there is subspecifically indistinguishable from ermines from farther west, audax is a synonym of Putorius arcticus.

1904. imperii (Putorius arcticus) Barrett-Hamilton [= Mustela erminea richardsonii], Ann. and Mag. Nat. Hist., ser. 7, 13:392, May, 1904, based on an animal from Fort Simpson, Mackenzie, Canada, proves to be inseparable from richardsonii which has priority.

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1904. polaris (Putorius arcticus) Barrett-Hamilton [= Mustela erminea polaris], Ann. and Mag. Nat. Hist., ser. 7, 13:393, May, 1904, is the name used for the ermine of eastern Greenland and since 1945 has been used for the weasel of Greenland as a whole.

1905. macrophonius (Putorius) Elliott [= Mustela frenata macrophonius], Proc. Biol. Soc. Washington, 18:235, December 9, 1905, applies to the long-tailed weasel of the mountains along the eastern border of Veracruz.

1906. leptus (Putorius streatori) Merriam [= Mustela erminea murica], Proc. Biol. Soc. Washington, 16:76, May 29, 1903, until 1945 was applied to the diminutive ermine of the Rocky Mountains from Wyoming south to northern New Mexico but proves to be a synonym of muricus with type locality in the Sierra Nevada of California.

1908. angustidens (Putorius cicognanii) Brown [= Mustela erminea angustidens], Mem. Amer. Mus. Nat. Hist., 9(pt. 4):181, pl. 17, is applied to an extinct subspecies known from fossil remains of Pleistocene age from northern Arkansas.

1908. gracilis (Putorius) Brown [= Mustela frenata gracilis], Mem. Amer. Mus. Nat. Hist., 9(pt. 4):182, 1908, applies to a Pleistocene weasel known from a single skull from northern Arkansas.

1912. costaricensis (Mustela) Goldman [= Mustela frenata costaricensis], Proc. Biol. Soc. Washington, 25:9, January 23, 1912, applies to the long-tailed weasel of Costa Rica.

1913. primulina (Mustela) Jackson [= Mustela frenata primulina], Proc. Biol. Soc. Washington, 26:123, May 21, 1913, applies to the long-tailed weasel of the central part of the United States in eastern Kansas and adjoining areas.

1913. campestris (Mustela) Jackson [= Mustela rixosa campestris], Proc. Biol. Soc. Washington, 26:124, May 21, 1913, applies to the least weasel of the Great Plains region.

1913. olivacea (Mustela peninsulae) Howell [= Mustela frenata olivacea], Proc. Biol. Soc. Washington, 26:139, May 21, 1913, applies to the long-tailed weasel of the southeastern United States excepting most of Florida.

1914. meridana (Mustela) Hollister [= Mustela frenata meridana], Proc. Biol. Soc. Washington, 27:143, July 10, 1914, applies to the long-tailed weasel of northern South America.

1916. nicaraguae (Mustela tropicalis) Allen [= Mustela frenata nicaraguae], Bull. Amer. Mus. Nat. Hist., 35:100, April 28, 1916, applies to the long-tailed weasel of Nicaragua.

1927. arthuri (Mustela noveboracensis) Hall [= Mustela frenata arthuri], Proc. Biol. Soc. Washington, 40:193, December 2, 1927, applies to the long-tailed weasel of Louisiana and adjoining areas.

1932. semplei (Mustela arctica) Sutton and Hamilton [= Mustela erminea semplei], Ann. Carnegie Mus., 21(2):79, February 13, 1932, originally was applied to the ermine of Southampton Island but after 1945 was applied also to the ermine of Baffin Island, Melville Peninsula and the west side of Hudsons Bay as far south as Eskimo Point.

1932. panamensis (Mustela frenata) Hall, Proc. Biol. Soc. Washington, 45:139, September 9, 1932, applies to the long-tailed weasel of Panamá.

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1932. anguinae (Mustela cicognanii) Hall [= Mustela erminea anguinae], Univ. California Publ. Zoöl., 38:417, November 8, 1932, applies to the ermine of Vancouver Island, British Columbia.

1935. labiata (Mustela arctica) Degerbøl [= Mustela erminea semplei], Rept. 5th Thule Exped., 1921-1924, vol. 2, no. 4, p. 25, 1935. When Degerbøl wrote his description and proposed this name he was unaware that Sutton and Hamilton had three years before based a new name on weasels from Southampton Island. Because the two names apply to the same subspecies, Degerbøl's name, labiata, must fall as a synonym of semplei which has priority.

1935. helleri (Mustela frenata) Hall, Proc. Biol. Soc. Washington, 48:143, August 22, 1935, applies to the long-tailed weasel of eastern Perú.

1936. nevadensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 91, November 20, 1945, applies to the long-tailed weasel of the western United States. For many years, animals of this subspecies were referred to longicauda and from 1891 until 1936 to arizonensis.

1936. effera (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 93, November 20, 1945, applies to the long-tailed weasel of the Blue Mountains region. From 1891 until 1936 this animal was referred to under the name arizonensis.

1936. altifrontalis (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 94, November 20, 1936, applies to the long-tailed weasel of the humid coastal district from Puget Sound southward into Oregon.

1936. nigriauris (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 95, November 20, 1936, applies to the long-tailed weasel of the coastal district of California from San Francisco Bay southward to Point Concepcion. Previous to 1936, xanthogenys was the name applied to this race of weasel.

1936. latirostra (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 96, November 20, 1936, applies to the long-tailed weasel of southern California which previously had borne the name xanthogenys.

1936. pulchra (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 98, November 20, 1936, is applied to the long-tailed weasel of the southern end of the San Joaquin Valley of California.

1936. inyoensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 99, November 20, 1936, is applied to the long-tailed weasel of Owens Valley, California.

1936. texensis (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 99, November 20, 1936, applies to the long-tailed weasel of central Texas which previously had been assigned to the subspecies frenata.

1936. perotae (Mustela frenata) Hall, Carnegie Inst. Washington, publ. no. 473, p. 100, November 20, 1936, applies to long-tailed weasel of the mountains along the Puebla-México boundary.

1938. boliviensis (Mustela frenata) Hall, Proc. Biol. Soc. Washington, 51:67, May 18, 1938, applies to the southernmost known long-tailed weasel which is in the Lake Titicaca region in Perú and Bolivia.

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1944. salva (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:35, June 28, 1944, applies to the ermine of Admiralty Island, southeastern Alaska.

1944. initis (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:37, June 28, 1944, applies to the ermine of Baranof and Chichagof islands, southeastern Alaska.

1944. celenda (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:38, June 28, 1944, applies to the ermine of Prince of Wales, Dall and Long islands, Alaska.

1944. seclusa (Mustela erminea) Hall, Proc. Biol. Soc. Washington, 57:39, June 28, 1944, applies to the ermine of Suemez Island, southeastern Alaska.

1945. invicta (Mustela erminea) Hall, Jour. Mamm., 26:75, February 27, 1945, applies to the ermine of the Rocky Mountains for several hundred miles both north and south of the United States-Canadian boundary.

1945. fallenda (Mustela erminea) Hall, Jour. Mamm., 26:79, February 27, 1945, applies to the ermine of the coastal mainland in southern British Columbia and northern Washington.

1945. olympica (Mustela erminea) Hall, Jour. Mamm., 26:81, February 27, 1945, applies to the diminutive ermine of the Olympic Peninsula, state of Washington.

1945. gulosa (Mustela erminea) Hall, Jour. Mamm., 26:84, February 27, 1945, applies to the diminutive ermine of the Cascades in Washington.

1945. bangsi (Mustela erminea) Hall, Jour. Mamm., 26:176, July 19, 1945, is the name applied today to the ermine of the western Great Lakes region.

In 1925 when this study was begun, the American weasels (subgenus Mustela proper) were arranged as belonging to 47 kinds (including subspecies) of 29 full species. In the present account a total of 68 kinds, belonging to 4 full species are recognized in the subgenus Mustela. The increase in number of subspecies and the decrease in number of species are the nomenclatural results ordinarily obtained in this decade from a systematic study of a genus of American mammals.

CHECK-LIST OF AMERICAN SPECIES AND SUBSPECIES OF THE GENUS MUSTELA

ARTIFICIAL KEY TO AMERICAN SPECIES OF THE GENUS MUSTELA

DIAGNOSIS OF THE GENUS

Genus Mustela Linnaeus

Weasels, Ferrets, Polecats, Minks

Genotype.—Mustela erminea Linnaeus.

Diagnosis.—Legs short; body relatively long; adults 190 mm. to 700 mm. in total length; skull ranging in basilar length from 16 to 70 mm.; facial angle slight; tympanic bullae greatly inflated (moderately in Lutreola), cancellous, and with paroccipital processes closely appressed to bullae; palate behind upper molars; dental formula:

  I  3  C  1  P  2-3  M  1
  -, -; -, -; -, ---; -, -;
  i  3  c  1  p  3-2  m  2

inner moiety of M1 larger than outer; P4 with simple deuterocone; in m1 trigonid longer than talonid, metaconid absent (incipiently developed in Lutreola), and talonid trenchant.

For many years prior to 1911, the name Mustela was applied to martens, and Putorius was regarded as the first available generic name for the weasels. In 1911 Thomas (1911:139) showed that M. erminea (Mustela of Gesner) by tautonymy was the type of Mustela and subsequently the generic name Mustela has been used for the true weasels which include the American weasels to which we now apply the specific names erminea, rixosa and frenata. The mink, Mustela (Lutreola) vison, and the black-footed ferret, Mustela (Putorius) nigripes, since 1911 also have been referred by most American authors to the genus Mustela, the names Lutreola and Putorius being regarded by these authors as having no more than subgeneric status. European writers, on the other hand, accord greater taxonomic weight to the zoölogical differences between ferrets and weasels and, therefore, accord full generic rank to Putorius. Consequently, for the black-footed ferret, Europeans today write Putorius nigripes and Americans write Mustela nigripes. For the same reasons, the name of the mink is written by some European zoölogists Lutreola vison and by American zoölogists Mustela vison.

EXPLANATION OF SYSTEMATIC TREATMENT

For each full species there will be found under the account of it the following information: Type, statement of geographic range, selected characters for ready recognition, other characters of the species, a summary of geographic variation, and information on habits, in the order mentioned.

For each subspecies, information is presented in the following order: earliest available zoölogical name, synonyms, type, geographic range, zoölogical characters for ready recognition, description (mentioning size, certain external features including color, the skull and teeth) historical material when warranted, remarks which may elaborate on points made in preceding paragraphs, and other information thought to be useful, and finally a list of specimens examined.

In explanation of certain of these categories it should be said that in the synonymy no attempt is made to list every published reference to the subspecies concerned. It is aimed, however, to include at least one citation to each name-combination that has been applied, to the subspecies concerned, along with other especially important references. Mere records of occurrence are not regarded as especially important and citations to them ordinarily are omitted in the synonymy. No comma is placed between the zoölogical name and the name of the author who coined and first used the name in accordance with the rules of zoölogical nomenclature. Otherwise a comma is interposed between the zoölogical name and the name of the user (author). When the accepted (earliest available) name of a subspecies at the head of any one of the following accounts is combined with a generic name different from that with which it originally was placed, the authority for the name is set in parentheses. The same rule is followed with the name of a full species when it is written without any subspecific name following. Parentheses in such situations, therefore, denote that for the terminal part of the scientific name there has been a change in generic name with which the terminal part of the scientific name is here associated.

In the paragraph headed "characters for ready recognition," only a few characters, namely, those regarded as most useful for identification when the student has limited time, are mentioned. Other features useful for distinguishing the kind of animal in question from its near relatives are to be found in the description and comparisons.

In the description, external measurements, unless otherwise indicated, are those recorded by the collector on the label attached to the skin. Total length is the distance from the tip of the pad on the nose to the tip of the fleshy part of the tail when the relaxed animal is laid out straight, not stretched. This measurement does not include the hairs that project beyond the end of the fleshy part of the tail. Length of tail is the distance from the base of the tail, when it is bent at right angles to the long axis of the body, to the tip of the fleshy part of the tail excluding the hairs that project beyond the fleshy part of the tail. Length of tail and length of tail-vertebrae are synonymous. Length of hind foot is measured from the proximal end of the calcaneum to the tip of the longest claw.

Capitalized color terms, unless otherwise indicated, refer to Ridgway's (1912) Color Standards and Color Nomenclature. Some use is made of color terms taken from Oberthür and Dauthenay (1905) because those authors show a much larger number of shades between dark brown and black than does Ridgway (1912). The colors of the upper parts of most weasels are some shade or other of dark brown. Color terms that do not have the initial letter capitalized do not refer to any one standard and consequently are used in a general sense.

Relative extents of the color of the upper parts and underparts are computed from measurements of the circumference of the body at the place where the color of the underparts is narrowest. Ordinarily this place is in the lumbar region rather than in the thoracic region.

An explanation of how cranial measurements were taken is given on page 417. In designating teeth, capital letters are used for teeth in the upper jaw and lower case letters are used for teeth in the lower jaw. For example: I2 denotes the second incisor tooth in the upper jaw and i2 denotes the second incisor tooth in the lower jaw; C1 and c1 refer to the canine tooth of the upper jaw and lower jaw, respectively; P3 and p3 refer to the third premolar of the upper jaw and lower jaw, respectively, bearing in mind that the first (anterior) premolar is absent in the lower jaw and upper jaw of weasels (see fig. 31 on page 416), as also, in some kinds of weasels, is the second premolar; M1 and m1 refer to the first molar of the upper jaw and lower jaw respectively.

In describing the skull and teeth the two sexes are treated separately because differences in shape as well as size are the rule. Unless otherwise indicated, the skulls on which descriptions are based are of adults. Weights of skulls include the weight of the lower jaws. In general, every second subspecies is described. For a subspecies geographically next adjacent to the one described, only the differences between the two are enumerated. This method of description indicates also likenesses and is more economical of words than some other methods of description. Also, by use of this method, cross reference is reduced to one other subspecies. Following this formal description, there is a comparison of the cranial and dental characters with those of geographically adjacent subspecies.

In the paragraph headed "Remarks" the two words "character" and "structure" frequently appear. The word structure here is used to mean some part of an animal, as for example, a hair, a muscle, a bone, or an internal organ. A structure is not a system, as for example, the digestive system or osseous system. A character is some weight, linear dimension, volume, shape, color, or other perceptible attribute of a structure, of a system, or of an entire organism.

In recording the localities of capture of specimens examined, effort has been made to be exactly as precise as the locality data on the labels of the specimens permit. The word "County" is written out in full when the name of the county is written on the label of each specimen listed from that county. When one specimen, or more, here assigned to a given county lacks the name of the county on the label, then the abbreviation "Co." is used. The surprising frequency with which the same place name is repeated in a given state or province makes it desirable for the collector to write the name of the county, or corresponding minor political subdivision, on labels of study specimens at the time they are prepared.

SYSTEMATIC ACCOUNTS OF SPECIES AND SUBSPECIES

MUSTELA ERMINEA Linnaeus

Ermine

(Synonymy under subspecies)

Type.—Mustela erminea Linnaeus, Systema Naturae, 10th ed., p. 46, 1758.

Range.—From the British Isles and Atlantic Coast of Europe across Eurasia and North America including Greenland, from the northernmost land, south, in North America, to the lower margin of the Canadian Life-zone; geographically south to Connecticut, New York, Pennsylvania, northeastern Ohio, southern Michigan, Wisconsin, northern Iowa, Minnesota, North Dakota, in the Rocky Mountains to northern New Mexico, in the Sierra Nevada to Mono County, California, and on the Pacific Coast to the Golden Gate.

Characters for ready recognition.—Differs from Mustela rixosa in presence of black pencil on tail, tail-vertebrae more than a fourth of length of head and body, and in regions where the two species occur together, basilar length of skull more than 32.5 in males and more than 31.0 in females; from Mustela frenata, in regions where the two species occur together, by tail less than 44 per cent of length of head and body and by postglenoidal length of skull more than 46 per cent of condylobasal length in males and more than 48 per cent in females.

Characters of the species.—Size medium to small (total length 225 to 340 mm. in males and 190 to 290 mm. in females); tail 30 to 45 per cent of length of head and body, with distinct black pencil; caudal vertebrae 16 to 19; skull with long braincase and short precranial portion; postglenoidal length, when expressed as a percentage of the condylobasal length, more than 48 in females and ordinarily more than 46 in males; upper parts brown; underparts whitish, ordinarily continuous from chin to inguinal region but in subspecies in the humid region along the Pacific Coast interrupted in some individuals by brown of upper parts encircling body in the abdominal region. The soles of the feet in each of the subspecies are densely haired in winter and have only a relatively small area of the foot-pads exposed in summer, the intervening areas being well haired even at that season. The uniformity throughout the species as regards hairiness of the foot-soles and also the character of the vibrissae makes it unnecessary to describe these features in the accounts of the subspecies of erminea.

Geographic variation.—In the Old World 16 or more subspecies are currently recognized and there are 20 in North America. The features in which geographic variation is especially prominent are: First, size, as expressed by external measurements and weight, second, color pattern, depending on the extent, in relation to one another, of the dark-colored upper parts and light-colored underparts, and third, breadth and depth of the rostral region of the skull. Except in size, the variation in the skull is less than in M. frenata. Likewise in tone and shade of upper parts and hue or tint of underparts, erminea is less variable than frenata and has the face all of one color without the contrasting color-pattern of the face and head seen in many subspecies of frenata. M. erminea exceeds frenata as regards variation of the size of the area occupied by the light-colored underparts. At one extreme is the subspecies arctica in which the area of the light color extends well up on the sides of the body, down the insides of the legs, over the feet and far out on the lower side of the tail whereas at the other extreme are the races streatori and olympica in which the light-colored underparts are restricted to two areas, one on the chin, throat and chest, and the other on the inguinal region. These areas may or may not be connected by a thin line of white color along the midline of the underparts. In size of animal, erminea probably exhibits the maximum variation among American species of weasels; an average-sized male of the race arctica weighs 4 times as much as one of the race muricus, and in the species frenata I doubt that the difference is quite as great between individuals of the smallest race, effera, on the one hand, and either of the largest races, texensis or macrophonius, on the other hand although actual weights are not available for these races of frenata. As elsewhere indicated, the small-sized individuals of M. erminea are of the southern races and the large-sized individuals are of the northern races. This decrease in size southward occurs both in Asia and in America.

Natural History.—Habitat and numbers.—Along the International Boundary east of the Turtle Mountains, Soper (1946:136) found this species present only in timbered areas and absent from many untimbered areas. Of the same species to the westward he comments "so far as I know at present, there is no evidence to show that any short-tailed weasels inhabit a broad strip of treeless territory immediately north of the International Boundary in Canada from southwestern Alberta to southeastern Saskatchewan." The same author (1942) reports that in the general area of Wood Buffalo Park, Northwest Territory, south of Great Slave Lake, the ermine is uncommon on pine-grown sand ridge and rolling upland and common in lower spruce-aspen parklands, stream-side coniferous belts, and grassy, semi-wooded swamplands.

Nine ermines per square mile is the number that Soper (1919:46-47) estimated at Edmonton on the basis of the numbers that he trapped there in the winters of 1912-13 and 1913-14 and on the basis of the tracks of remaining ermines. From corresponding data he estimated the population in the winter of 1913 on the Hay River, north of Jasper Park, to be nine per square mile. In each of these instances he estimated ten weasels per square mile but he inclined to the view that one-tenth of the animals involved in his counts were long-tailed weasels (Mustela frenata). Osgood (1909B:30) and his field companion in the period July 31 to September 3, 1903, took a series of 42 specimens within a radius of 500 yards of their camp at the head of Seward Creek, Alaska, all caught in four traps, in one month. Of the 42 specimens, 28 are males and 14 are females.

Fluctuations of a multiannual nature are marked in this species. Bailey (1929:156) observes that in Sherburne County, Minnesota, when meadow mice are abundant for two or three years these weasels become abundant but that when the mice are scarce the weasels also become scarce. Manning (1943:56), on Southampton Island, noted "that the maximum and minimum points of the weasel cycle are much more sharply marked than those of the fox cycle and the increase and decrease are more rapid."

How far an ermine will travel in a given length of time has seldom been recorded but Hamilton (1933:293), on March 20, 1932, "followed the track of a small weasel, presumably a male cicognanii, for four miles in the fresh snow," and Ingles (1942) observed a diminutive ermine of the subspecies M. e. muricus, at Woods Lake, California, 286 yards from its den.

Behavior

As regards locomotion, Soper (1919:46), in reference to Mustela cicognanii, presumably in Ontario, Canada, writes that in the bounding gait the hind feet register almost, if not exactly, in the front-foot impressions, with the right front and hind feet lagging slightly behind. "The distance normally is about 19 inches, representing a regular rate of travel. . . . In traversing open spaces they resort to long, graceful leaps upwards of six feet in length. . . . I measured a record . . . of 8 feet, 2 inches."

Of M. e. arctica, Dice (1921:22) writes that when it runs "the tail is carried off the ground usually at an angle of about 45 degrees." Seton (1929 (2):598) states that "At Carberry [Manitoba] I have often seen this energetic little creature seeking for Mice in the deep, soft snow. Its actions are much like those of an Otter pursuing salmon. Sometimes it gallops along a log, or over an icy part of the drift; then plunges out of sight in a soft place, to reappear many yards away. . . ."

Little is recorded concerning swimming but on this score Seton (1929 (2):602) does quote J. W. Curran, who in July, 1899, at Lake Couchiching, Ontario, watched an ermine pursue a chipmunk into the water and for 100 yards before giving up the chase and wheeling around and making for shore. In swimming "The Weasel, I think, showed more of his body, and seemed to exert himself more" than the chipmunk.

As to voice, Dice (1921:22), at Tanana, Alaska, heard the ermine, when excited, bark somewhat like a mink but not so loud and Seton (1929 (2):606) quotes Manley Hardy to the effect that the species has a purring note.

Sense of smell was used by an M. e. muricus that Dixon (1931:72) watched as the ermine followed a three-fourths-grown pika. Concerning the ermine at Carberry, Manitoba, Seton (1929 (2):598-599) writes that "The smell of blood must be as far-reaching as it is attractive to these sanguinary little creatures. I have frequently hung new-killed Rabbits and partridges temporarily in trees, and, after an absence, in some cases of a few minutes only, have found an Ermine mauling the game, though there was no sign of such a visitor when the cache was made."

Enemies

George Measham, of Winnipeg, found sign in the snow indicating that a great snowy owl had killed an ermine and T. McIlwraith shot a bald eagle at Hamilton Bay which had the bleached skull of a weasel (probably of this species) clinging to the throat (Seton, 1929 (2):603).

A. B. Howell (1943:98) likens mustelid mammals to domestic cats in their manner of crossing roads and thinks that mustelids loiter at the side of the road until the stimulus of the approaching car causes them to make a dash whereupon they are caught by the wheels and killed. Three of four weasels seen to cross the road were killed, one even having apparently crossed the road before turning back and being killed under the car. One weasel killed was Mustela erminea cicognanii. Dalquest (1948:190) in writing of this species in the state of Washington, says "I have seen only one abroad in the daytime. It dashed from a roadside thicket . . . and was crushed beneath the wheels of a car."

Food

The killing of prey is described by Hamilton (1933:332) as follows: "A rapid dash, and the bird or mouse is grabbed over the back of the skull, the fore legs encircle the animal as though hugging it, and the hind legs are brought up to scratch wildly at the captive. . . . If [the prey is] a large animal, as a rat, the weasel usually lies on its side, while the diminishing struggles of the rodent continue, but if a mouse or a small bird [is the object of attack], the weasel is apt to crouch over its prey. Little time is lost over the first [mouse] . . . if two mice are present [;] a strong bite through the brain case . . . [is] sufficient. If only one animal is present, the weasel dawdles over its kill some time after life has departed."

Hamilton's (1933:333) study of the contents of the digestive tracts of bodies of ermines obtained from fur trappers and fur buyers in New York enabled him to publish the following "Frequency Indices of Mammal Genera in Fall and Winter Food of 191 Mustela cicognanii": Microtus, 35.7 per cent; mammals undetermined to genus but principally mice, 16.3; Blarina, 15.1; Peromyscus, 11.4; Sylvilagus, 9.0; Sorex, 4.9; Rattus, 4.4; Tamias, 3.6. Close correspondence is shown by the following data of Aldous and Manweiler (1942) for the ermine from Lake of the Woods, Minnesota: mice, 58.7 per cent by number and 54.5 by volume; shrews 22.5 and 21.8 per cent; birds, 2.7 and 5.0 per cent. Of the mice in stomachs, 40 per cent were microtines, 15 per cent were Peromyscus and 45 per cent were unidentified as to kind. Fragments of a small fish were found in one stomach. Summed up, the dominant winter foods were mice and shrews. Trapping of the mammal populations was done to see what the available food was and it was found that the small mammals were eaten in direct ratio to their relative abundance. Snowshoe rabbits and red squirrels were not eaten. The Minnesotan data were from 60 stomachs and 53 intestinal tracts recovered from 129 weasels trapped by use of scent (not bait) mostly from January 1 to February 7, 1939, although a few were trapped in 1938. Analyses of contents from stomachs gave approximately the same results as those from intestines. In 1939 at Lake of the Woods, weasels were concentrated where food was abundant but no such concentration was noted in the following winter.

Big short-tailed shrew (Blarina brevicauda).—In New York State, the ermine preys on Blarina as shown by Hamilton's (1933:330) seeing one being carried by a male ermine on May 6, 1931, and another being carried by a female on May 13, 1932. The same author (1928:249) found the remains of a Blarina in a small female from Malone, New York. Kirk (1921) observed, however, that the ermine (M. e. cicognanii) avoided the shrew, Blarina, caught in a trap and that Blarina avoided the weasel caught in a trap.

Chipmunk (genus Tamias).—Remains were found in a male ermine in New York on May 14, 1932 (Hamilton, 1933:330), and Seton (1929 (2):602) records a chipmunk at Lake Couchiching, Ontario, that was pursued into the water by an ermine.

Deer mice (genus Peromyscus).—As shown by Hamilton (1933:33) and Aldous and Manweiler (1942), Peromyscus was second only to microtines in numerical abundance among the food items of ermines in New York and Minnesota. Peromyscus and microtine rodents were brought to a den of the diminutive M. e. muricus in early August, in Fresno County, California, according to Ingles (1942). He observed that an Alpine chipmunk was active under and around the tree and that juncos reared young 40 feet from the den but that the chipmunk and juncos were unmolested by the ermines.

Lemming (genus Lemmus).—One was recovered from a female ermine (with milk in her glands) at Laurier Pass, British Columbia (Sheldon, 1932:201).

Red-backed mouse (genus Clethrionomys).—Criddle and Criddle (1925:146) record that on "May 31, 1921.—Saw a Bonaparte's weasel capture a Red-backed Vole after a long hunt during which the pursuer never once lost track of its victim."

Meadow mice (genus Microtus).—As shown by the data of Hamilton (1933:333) and Aldous and Manweiler (1942) recorded above, Microtus is the item of first importance in the diet of the ermine in New York and Minnesota. Criddle and Criddle (1925:146) write concerning the vicinity of Treesbank, Manitoba, that "October, 1918.—Following a severe outbreak of mice in 1916-17, Bonaparte's weasel increased enormously and very soon reduced the rodents to comparative rarity. This resulted in a scarcity of food for the weasels, which in their turn became greatly reduced in numbers."

Old World rat (Rattus).—Bishop (1923) found two headless rats near a nest of this species in Albany, New York.

Pika (Ochotona).—Dixon (1931:72) at Milner Pass, Colorado, on July 20, 1931, saw an ermine, of the subspecies muricus, following a three-fourths grown pika by scent and outrunning the pika. The pikas worked a relay system and the weasel abandoned the trail when the fourth pika became the object of the chase.

Cottontail (genus Sylvilagus).—Hamilton (1933:33), as noted above, found remains of cottontail in the digestive tracts of ermine that had been trapped for fur in winter. Possibly these remains were bait that had been placed at traps.

Snowshoe rabbit (Lepus americanus).—Morse (1939:210) in a study of predation on hares and grouse in the period of notable decimation of these two game species in 1935-1936 in the Cloquet Valley State Forest, in St. Louis County, Minnesota, found that "weasel predation on hares appeared to be of very low incidence or altogether lacking."

Wild birds (Class Aves).—Aldous and Manweiler (1942), as noted above, found that the remains of birds constituted five per cent by volume of the food of the ermine in winter in Minnesota.

Chicken (genus Gallus).—Criddle and Criddle (1925:145), who published relatively extensive data on the three species of weasels of Manitoba, write that: "We have no record of Bonaparte's weasel killing poultry, and we doubt whether it ever does so." However, Soper (1919:46) investigated the excited cackling of a hen brooding chicks at night and found a solitary ermine that had killed three chicks and that had the remainder under very active scrutiny.

Leopard frog (Rana pipiens).—One frog was found in a male ermine on November 20, 1931, in New York by Hamilton (1933:300).

Fish (Class Pisces).—Aldous and Manweiler (1942) found fragments of a small fish in one of 60 stomachs of ermine from Minnesota.

Earthworm (Phylum Annelida).—Osgood (1936:64), presumably at Rutland, Vermont, observed a pair of weasels from 2:15 P.M. to 5:00 P.M., in a barn and saw the female in that time make many trips for food for her young. Only earthworms were brought. Fifty traps in an adjacent, swampy field caught only one bull frog and no mice indicating that mice had been eliminated from the foraging territory of the ermine.

In handling food, Dice (1921:22) noted that the Alaskan ermine did not use the feet but only the mouth.

Reproduction

Litters of 4, 4, 7, 7, and 8, yielding an average of 6 young per litter have been recorded from the northeastern United States by Hamilton (1933:327). He (op. cit.:321-325) described animals one day old from New York State as being flesh-colored, having the long neck of the adult and a fine growth of white hair two milli meters in length, on the dorsal surface of the neck, that foreshadows the mane or pompadour that is prominent from the 14th to the 21st day of life. Six animals, when one day old averaged 1.7 grams in weight, which was three per cent of the weight of an adult female and one and one half per cent of the weight of an adult male. At two weeks of age the heavy brown mane stood out in marked contrast to the rest of the scantily, white-furred animal. The eyes opened on the thirty-fifth day of life.

Fig. 24. Mustela erminea richardsonii, adult female, Catalogue Number 14866, U. S. Nat. Mus., Fort Chimo, Ungava. × 1/2.

Ventral view of body of a pregnant female to show details of mastology. Note the five pairs of mammae characteristic of weasels, and the uneven arrangement of mammae of the two sides which is also common among weasels.

Fig. 25. Map showing geographic ranges of the subspecies of Mustela erminea in the New World.

For rearing their young, ermines live in burrows. Bishop (1923), in Albany, New York, found a burrow occupied by four young and a pair of adults. The burrow had many galleries and contained a nest constructed of rat fur, fine grass and fragments of leaves. At Woods Lake, Fresno County, California, in early August, Ingles observed (1942) some young and at least one adult at their den which was in a burrow beneath a hollow tree. The ermines used the hollow root and the hollow tree as well as the burrow beneath. Seton (1929 (2):591) quotes S. Eldon Percival, of Barretts Rapids, Ontario, as finding the living quarters of an ermine in unthreshed grain stacked in a barn and says (op. cit.:590) that John Burroughs dug out a nest, composed of leaves and the fur of mice and moles, two or three handfuls in bulk, from a cavity the size of a hat, arched over with a fine network of tree roots.

Four instances in which the male as well as the female was present at a den containing young are cited by Hamilton (1933:328) and he gives some evidence, although not at all conclusive, that "adults customarily pair, or at least run together, at times other than the breeding season." No other writers remark on this matter. I doubt that adult ermines are associated in pairs for most of the year but such may be the case.

Mustela erminea arctica (Merriam)

Ermine

Plates 2, 3, 4, 9, 10, 11 and 41

Putorius arcticus Merriam, N. Amer. Fauna, 11:15, pl. 2, figs. 1, 1a, and pl. 5, figs. 6, 6a, June 30, 1896.

Putorius (Gale) erminea, Coues, Fur-bearing animals, p. 109, 1877 (part).

Putorius richardsonii, Bangs, Proc. Biol. Soc. Washington, 10:16, pl. 1, figs. 3, 3a, pl. 2, figs. 3, 3a, and pl. 3, figs. 6, 6a, February 25, 1896 (part).

Putorius cicognanii alascensis, Osgood, N. Amer. Fauna, 19:43, October 6, 1900.

Putorius kadiacensis, Osgood, N. Amer. Fauna, 21:69, September 26, 1901.

Putorius audax Barrett-Hamilton, Ann. and Mag. Nat. Hist., 13(ser. 7):392, May, 1904, type from Discovery Bay, Ellesmere Island.

Putorius alascensis, Heller, Univ. California Publ. Zoöl., 5:345, March 5, 1910.

Mustela arctica arctica, Miller, U. S. Nat. Mus. Bull., 79:97, December 31, 1912; Dice, Journ. Mamm., 2:22, February 10, 1921.

Mustela arctica, Hall, Univ. California Publ. Zoöl., 30:420, March 19, 1929.

Mustela erminea arctica, Ognev, The mammals of U.S.S.R. and adjacent countries, 3:31, 1935; Hall, Proc. California Acad. Sci., 23:559, August 22, 1944; Hall, Journ. Mamm., 26:179, July 19, 1945.

Type.—Male, adult, skull and skin; no. 14062/23010, U. S. Nat. Mus.; Point Barrow, Alaska; July 16, 1883; obtained by John Murdock, original no. 1672.

The skull has a fracture, on the dorsal surface, extending from the anterior nares to the interorbital constriction and another fracture on the left margin of the nasal bone. The middle of the left zygomatic arch is broken away. Otherwise the skull is complete. Right incisor one, above and below, are missing. Otherwise the teeth are present and entire. The skin is in the brown summer pelage, well made, in a good state of preservation, and shows no obvious signs of fading.

[97]

Range.—Arctic regions of Alaska and western Canada from the Pacific Ocean to Smith Sound; from the northern limit of land south approximately to a line from Skagway through Ft. Goodhope, north shore of Great Bear Lake, south shore of Clinton Colden Lake, north shore of Baker Lake, west end of Wagner Bay to south end of Committee Bay. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. polaris in darker upper parts (Raw Umber rather than Buckthorn Brown) and less intensely colored underparts that are Sulphur Yellow, Colonial Buff or Primrose Yellow rather than Buff Yellow; from M. e. semplei, in males, in that hind foot more than 44 and basilar length more than 41 and in that females average larger, the skulls of females being only about 11 per cent heavier; from M. e. kadiacensis in hind foot more than 33 in females, zygomatic breadth amounting to more, rather than less, than distance between last upper molar and jugular foramen irrespective of sex; from M. e. richardsonii, alascensis, salva and initis, both sexes so far as known, by proximal two-thirds of under side of tail colored same as underparts rather than same as upper parts, and by zygomatic breadth amounting to more, rather than less, than distance between last upper molar and jugular foramen.

Description.—Size.—Male: Six adults from Tanana, Alaska, yield average and extreme measurements as follows: Total length, 336 (310-350); length of tail, 93 (84-105); length of hind foot, 49 (45-51).

Female: Five adults, one each from Alatna River, mountains near Eagle, Kamarkak in Alaska, Arctic Red River and Baillie Island in Canada, yield average and extreme measurements as follows: Total length, 285 (272-304); length of tail, 77 (68-95); length of hind foot, 39 (34-43).

Weight of 5 subadult males from Tanana is 206 (163-248) grams; adults would be heavier.

Color.—Winter pelage all white except tip of tail. Summer pelage with upper parts uniform in color and Raw Umber or darker (16n) of Ridgway and about tones 2 to 3 of Chocolate of Oberthür and Dauthenay, pl. 343, but in autumn some specimens have more light red than tones 2 or 3. Underparts Sulphur Yellow, Colonial Buff, or Primrose Yellow, often white on chin and insides of forelegs; color of underparts extends narrowly over upper lips, distally on posterior sides of forelegs onto antipalmar surface of forefeet, onto proximal two-thirds or three-fourths of underside of tail as length of tail is measured along tail-vertebrae, on medial sides of hind legs to a point between knee and ankle but reappears on antiplantar faces of toes and in some individuals is narrowly continuous onto toes; rim of ear in some specimens with short, white or pale hairs giving ears distinct whitish border; least width of color of underparts averaging, in adult males from Alaska, 65 (46-93) per cent of greatest width of color of upper parts. Black tip of tail in 5 males in winter pelage from Tanana averaging 84 (70-93) mm. which is 91 (75-107) per cent of length of tail-vertebrae.

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Skull.—Male (based on 5 adult topotypes): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 3.5 (3.1-3.9) grams; basilar length 42.5 (41.8-43.3); length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes averaging more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen.

Female (based on 2 adult topotypes and 2 adults and 4 subadults from central Alaska): See measurements and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 1.5 (1.2-2.0) grams; basilar length, 35.7 (34.5-37.0); length of tooth-rows more than length of tympanic bulla; breadth of rostrum more than 30 per cent of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen (except in specimens from Ellesmere Island where two distances are approximately equal).

Cranial differences from Mustela erminea kaneii (which occurs on the Asiatic side of Bering Strait), in both males and females, are: larger size relatively as well as actually, broader except in mastoidal region where relatively (to basilar length) the width is less; preorbital part of skull broader as well as longer.

From kadiacensis differences in the skull of the male are: size less; 13 per cent heavier, relatively (to basilar length) narrower across interorbital region and zygomatic arches; tympanic bullae relatively as well as actually narrower. Judging by the single available adult female of kadiacensis, the skull of female arctica is larger in all parts measured, a fourth heavier, has tympanic bullae of almost twice the volume and the interorbital and preorbital regions, relative to the braincase, are much reduced in whatever plane measured.

Differences from richardsonii, additional to those noted above in the formal description of the skull, between the males, are: larger in all parts measured except length of tympanic bulla which is about the same; 42 per cent heavier; relative to basilar length, skull broader with preorbital part longer as well as broader; tympanic bullae more inflated posteriorly. The same differences prevail between females except that the skull is 36 per cent heavier and in arctica the length of the bulla is actually more (although relative to the basilar length less) and its greater inflation posteriorly is hardly perceptible. Differences from alascensis, additional to those indicated in the formal descriptions of the skulls of the two, in males, are: larger in every part measured; 95 per cent heavier; relative to the basilar length, skull broader with preorbital part longer as well as broader; measured at a point opposite the foramen lacerum anterius, the width of the pterygoid space is more, rather than less, than 40 per cent of its length. Excepting this difference in width of interpterygoid space, the same differences prevail between females, those of arctica being 56 per cent heavier.

Comparison with semplei is made in the account of that subspecies.

Skull indistinguishable from that of polaris.

Remarks.—The person who studies specimens of this subspecies finds labels inscribed with the names of naturalists well known to all readers of literature on the Arctic. Sir John Franklin, R. McFarlane, R. Kennicott, E. W. Nelson and R. M. Anderson are names which appear commonly. Of Alaskan specimens prepared according to modern methods, a large share was obtained by O. J. Murie and L. R. Dice.

The ermine was observed in the far north by early explorers and was mentioned in the literature, almost always under the name then used for the ermine of northern Europe and Asia. In 1896 Bangs misapplied to it the name richardsonii but Merriam in the same year corrected the application of this name and proposed as new for this weasel the name arctica, the name in use today. For almost 50 years after Merriam and Bangs wrote about it, arctica was treated, nominally at least, as a species distinct from its other relatives in both the Old- and New-World. The subspecific status of arctica was emphasized in 1944 (555) by the present writer in reporting in detail upon the specimens, of Mustela erminea, from Eastern Asia which were made available on loan by Professor B. S. Vinogradov and the late Anatol I. Argyropulo of the Leningrad Academy of Sciences. Specimens of Mustela erminea kaneii from the Asiatic side of Bering Strait and Mustela erminea arctica from the American side are distinguishable by slight cranial characters but in coloration and external measurements I can detect no differences. Merriam's (1896:16) mention of more golden-colored upper parts and darker underparts in American specimens than in erminea was the result of his comparison of Alaskan and northern European specimens. When Old World specimens from eastern Siberia, instead of from Europe, are used the differences mentioned by Merriam do not apply. Incidentally, many Siberian specimens have the white border, on the ear, which Merriam (loc. cit.) noted as a distinguishing feature of arctica. When Merriam named arctica he said (1896:15, 16) "Putorius arcticus . . . has heretofore been confounded with erminea or richardsonii. . . . It is interesting to find in this country an Arctic circumpolar weasel which, though specifically distinct, is strictly the American representative of the Old World erminea." Bearing in mind that Merriam's concept of species and subspecies (see Merriam, 1919:6) differed from that of nearly all modern systematists it is clear from his statement quoted above that he correctly understood the zoölogical relationship obtaining between the ermines of the Old and New Worlds.

Ognev (1935:31) seems to have been the first to use the name combination Mustela erminea arctica for Alaskan specimens. Thereby he expresses the view adopted here, namely that the American ermine is subspecifically but not specifically distinct from the Old World animal. Whether actual intergradation (crossbreeding) ever takes place across the narrow Bering Strait I do not know. I doubt that crossbreeding occurs but considering the Diomedes (islands), that might serve as a half way stopping point, and remembering Mr. Charles Brower's oral statement to me that he had seen tracks of ermine as far as 10 miles from the northern shore of Alaska out on the ice, the possibility must be granted of an occasional individual crossing from one side to the other of Bering Strait on the ice in winter or of being carried across when the ice broke up and drifted. If transfers of this kind occurred often one would expect ermines to occur also on Saint Lawrence Island where apparently they do not. The one skin (U. S. Nat. Mus. no. 259046) seen as labeled from there, my friend, Otto William Geist ascertained was imported as a skin with other furs from Siberia.

Ognev (op. cit.) who used the name combination Mustela erminea arctica for Alaskan specimens, applied it also to animals from Kamchatka. At the same time he recognized the animal from the eastern mainland of Siberia (as opposed to the peninsula of Kamchatka) under the name Mustela erminea orientalis Ognev 1928. Hall (1944:556) applied the earlier proposed name Putorius kaneii Baird 1857, to the animal on the eastern mainland of Asia and proposed the new name Mustela erminea digna for the ermine of Kamchatka. In comparing material of these two Asiatic races with topotypes and other specimens of M. e. arctica from Alaska, it seemed to me that the degree of relationship, one with the other, was about the same. M. e. digna has a slightly larger preorbital region than M. e. kaneii, and the skull is longer. In both of these particulars digna approaches closer to arctica. M. e. kaneii has longer tympanic bullae and a wider skull than digna and therein approaches more towards arctica than toward digna. As nearly as I can make out, digna and kaneii show a nearly equal degree of resemblance to arctica. Also the degree of difference between digna and kaneii is about the same as between either one of them and arctica. In view of the above considerations the ermines of the New and Old worlds are here regarded as only subspecifically distinct.

In the original description of Putorius audax (here regarded as inseparable from Putorius arcticus Merriam) Barrett-Hamilton erroneously designated the type locality as "Discovery Bay, North Greenland" whereas he should have written Grinnell Land [= Ellesmere Island of modern terminology] in place of Greenland. As reference to Nares (1877 and 1878) will readily reveal, Discovery Bay is near 65° W and 81° 40´ N, across Robeson Channel, to the west, from Greenland. The label on the type specimen and the specimen register in the British Museum of Natural History each designates the locality for this specimen, the type of audax, as Discovery Bay without mention of Greenland. The published accounts of Feilden (1878) and Nares (1877 and 1878) state that specimens of ermine were obtained at Discovery Bay. Probably H. C. Hart is the collector of the specimen; he was the naturalist attached to H. M. S. Discovery which wintered at Discovery Bay while H. W. Feilden was the naturalist attached to H. M. S. Alert which wintered a few miles southeast of Cape Sheridan, also on the eastern coast of Ellesmere Island.

It is true that from these ships a trip was made into Greenland and an ermine (only one individual it seems) was obtained there, but this individual was the type specimen of Mustela erminea polaris, in the account of which race something of the history of this specimen is given.

With the material available—and it is not entirely adequate—I can detect no features by which animals from the type locality of audax can be distinguished from typical arctica which latter name has priority.

Intergradation with richardsonii probably occurs completely across the continent. Intergrades here referred to arctica include those from Fort Goodhope. The one defective specimen from Lake Lebarge, Yukon, is not certainly identified as arctica and how far west of Teslin Lake the boundary-line between arctica and richardsonii should be drawn remains to be ascertained. The one specimen available from Hinchenbrook Island, no. 912 Mus. Vert. Zoöl., an adult female, is doubtfully referred to arctica because the damaged tympanic bullae appear to be no larger than in alascensis, and the size of the skull is more as in alascensis although intermediate between that race and arctica. Shape of the skull is more as in arctica. Possibly more nearly adequate material would show the existence on Hinchenbrook Island of an insular race differing in about the same degree from arctica of the mainland as does the insular kadiacensis. Nevertheless, the males from farther south at Cape Yakataga are in all respects arctica and this argues against near relationship to alascensis of the animal on Hinchenbrook Island. The three animals seen from Yakutat Bay are so young as not to display clearly the cranial characters of the subspecies but the extension of the color of the underparts onto the underside of the tail in them and also in the skin without corresponding skull from Glacier Bay, Alaska, is as in arctica, the race to which they are referred, and gives substantial basis for showing the geographic range of arctica as extending this far south along the Pacific Coast.

Specimens examined.—Total number, 281, arranged alphabetically by Districts and from north to south in each District. Unless otherwise indicated, specimens are in the collection of the United States National Museum.

Alaska. Point Barrow, 22 (1[1], 1[2], 1[75], 4[1], 7[60], 6[74]); Flaxman Island, 3; Collinson Point, 1[77]; Salirochet River, 1[77]; Hulahula River, 1[2]; 69°20´ & 141°, 1; Rampart House, 1; Yukon River, mouth of Porcupine River, 18; Alatna River, 30 mi. from mouth, 1; Koyakuk Riv., 16 mi. below Bettles, 4; Shelton, 1[75]; Kruzamepa, 1[75]; Tanana, 6; Boulder Creek, Chena River, 3; Fort Reliance, 4; Yukon River, 20 miles above Circle, 2; Mts. near Eagle, 42 (1[60]); Snake River, Nome, 1[9]; Nulato, 3; No[e]wikakat Riv., 1; Kantishna, 3; Fairbanks, 5 (1 20 mi. E and 1 33 mi. E); Richardson, 1; N. Fk. Kuskokwim R. at base of Mt. Sischo, 1; N. Fk. Kuskokwim R. at Junction with McKinley Fk., 1; Nenana Riv., mouth of Maurice Cr., 1; Ober Cr., trib. of Jarvis Cr., Delta Riv. region, 1; head of Savage Riv., near Jennie Cr., 1; Wonder Lake, 1[74]; Bear Cr., 3; Unlakleet, 3; St. Michaels, 11; 125 mi. E and a little N of Knik, Cook Inlet, on S side Matanuska Range, 1[60]; Hope, Cook Inlet, 1; Iak Lake, 1[68]; head of Behring Riv., 1; Bethel, 2; Kenai Lake, 8; Kenai Peninsula, 13 (2[2]); He[i]nchenbrook Island, 1200 ft., 1[74]; Sunshine Point, Kaliekh River, Yakataga Dist., 1[8]; Cape Yakataga, 3[8]; Yakutat Bay, 3[74]; Seward, 7; Seldovia, 22 (4[2]); Homer, 1[2]; Cape Elizabeth, 18; Akchookuk Lake, 1; Lake Weelooluk, 1; Kokwok Riv., 80 mi. up, 4; Nushagak, 1; Nushagak Riv., 1; Kolukuk, 1; Egooshik River at mouth, 1; Glacier Bay, 1; Becharof Lake, between Portage Bay and Becharof Lake, 1; Ugashik Riv., 4; Chignik, 7; East base Frosty Peak, 1; Pavlov Bay, 1[100]; Mt. Pavlof, 1[75]; Unimak Island, 2 (1[75]).

District of Franklin. Cape Sheridan, 1[2]; Discovery Bay, Ellesmere Island, 1[7] (type specimen of Putorius audax Barrett-Hamilton); Axel Heiberg Island, 1[95]; Bache Peninsula, Ellesmere Island, 1[77]; Bedford Pims Island, 4[75]; Craig Harbor, 2[77]; Cape Kellett, Banks Island, 1[77]; Franklin Isthmus, 1[95]; King William Island, 2[95].

District of Keewatin. Ualiak, Ogden Bay, 2[95].

District of Mackenzie. Baillie Island, 1[75]; Franklin Bay, 1; Langton Bay, arm of Franklin Bay, 15 mi. S of, 1[2]; Cockburn Point, 69°N, 115°W, 2[77]; Dolphin and Union Strait, 1[77]; Bernard Harbor, 2[77]; Kent Peninsula, 4[95]; Horton Riv., near Fort Anderson, 1; Fort Anderson, 6; Anderson River, 3; Barry Island, Bathurst Inlet, 1[77]; Fort McPherson, 1; Peels River, 2; Arctic Red River, 8[75]; Fort Good Hope, 6; Clinton Colden, 1[2].

Yukon. Kamarkak, 1[77]; Herschel Island, 1[75]; Lapierres House, 2; Forty Mile, L. T. Coal Cr., 4[74]; head of Coal Cr., 1; Macmillan River, Forks, 1; 20 mi. W. Ft. Selkirk, 1; Slims River, near Kluane, 1[75]; head of Lake Lebarge, 1.

Mustela erminea polaris (Barrett-Hamilton)

Ermine

Putorius arcticus polaris Barrett-Hamilton, Ann. and Mag. Nat. Hist., 13 (ser. 7):393, May, 1904.

Mustela erminea, Manniche, Meddelelser om Grønland, 45:80-85, 1 fig., 1910.

Mustela arctica polaris, Miller, U. S. Nat. Mus. Bull., 79:97, December 31, 1912.

Mustela erminea polaris, Hall, Journ. Mamm., 26:179, July 19, 1945.

Type.—Probably female, skin only; no. 78. 6. 19. 11, Brit. Mus. Nat. Hist.; Gap Valley, 7-1/4 miles northeast Cape Brevoort, 82° N, 59° 20´ W, Northwestern Greenland; June 15 or 16, 1876; obtained by Lewis A. Beaumont.

The skin is in full, fresh summer pelage, fairly well stuffed except for the tail which is unstuffed; the whole is in a good state of preservation.

Range.—North coast, and east coast as far south as Turner Sound (between 69 and 70 degrees) of Greenland. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. arctica in lighter upper parts (near [j] Buckthorn Brown rather than Raw Umber or darker) and more intensely-colored underparts that are Buff Yellow rather than Sulphur Yellow, Colonial Buff, or Primrose Yellow; from M. e. semplei in color in same fashion as from arctica and in larger size of skull.

Description.—Size.—Male: One subadult and two adults (one ad. from Scøresby Sound and other two from Ymer Island) measure as follows, the average being given first: Total length, 318 (301, 320, 315); length of tail, 72 (69, 70, 73); length of hind foot, 46.5 (44, 46, 47).

Female: No measurements taken in the flesh available but hind foot, measuring 33.5 in the dried state and therefore approximately 35 in life.

Color.—As described in Mustela erminea arctica except that upper parts in summer near (j) Buckthorn Brown and tone 4 of Dark Fawn of plate 307 to tone 1 of Raw Umber of plate 301 of Oberthür and Dauthenay. Underparts Buff-Yellow. Least width of color of underparts averaging, in 3 males, 66 (57-72) per cent of greatest width of color of upper parts. Black tip of tail in same males averaging 71 (70-72) mm. which is 99 (99-104) per cent of length of tail-vertebrae.

The lighter-colored upper parts and more intensely yellow underparts are the distinguishing features of the subspecies polaris in comparison with other races of American M. erminea.

Skull.—Male (based on 5 adults from eastern Greenland): See measurements. As described in Mustela erminea richardsonii except that: Weight more (not recorded); basilar length, 41.3 (39.0-42.4); length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes averaging more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen.

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Female (based on 2 adults, Turner Sund and Kap Hoeg): See measurements. As described in Mustela erminea arctica except that basilar length 36.8 (35.9, 37.8), and length of tooth-rows not more than length of tympanic bulla. Skulls of females not in hand when this comparison is written; only the recorded measurements are available.

To me the skull of polaris is indistinguishable from that of arctica. Therefore the comparisons made of the skull of arctica with those of other subspecies will apply also for polaris.

Remarks.—In view of the heretofore erroneous assignment of the type locality of Mustela erminea audax to Greenland, pains were taken to verify the statement by Barrett-Hamilton (1904:393) relative to the type specimen of polaris. Taking pains thus seemed the more worthwhile because in the specimen register at the British Museum of Natural History, there is written to the right of catalogue numbers 78-6 = 19 nos. 1-11, "Discovery Bay Presented by Mr. Hart Arctic Collection." This refers to no. 78.6.19.1. There are no ditto marks below but by implication this data applies also to nos. 1-11, which include the holotype of polaris. A label attached to the specimen does however give the locality as "Hall Land" "N Greenland" and another label has on it "Ermine, procured by Mr. Beaumont Greenland Lat 89° Long W 59-20." The 89° is obviously a mistake (on the label or in my transcription of it) for 82°.

Reference to Nares (1877:385) reveals that Lieutenant Lewis A. Beaumont, under date of June 15 and 16, 1876, wrote in his field journal as follows: "I shot an ermine." In the daily accounts of his journey from Discovery Bay on Grinnell Land [= Ellesmere Island], across Robeson Channel and along the north coast of Greenland to the west base of Mount Farragut near 50° 30´ W he mentions the ermine only this once. For several other kinds of animals, Beaumont mentions individuals seen or shot, often with the notation that this is the second, or third seen. This mention of a kind of animal whenever seen was in accordance with orders. On page 39 of the Discovery Report (op. cit., 1877) in "General orders to sledging parties" by Captain G. S. Nares, Commanding the Expedition, we find ". . . note daily: IV State the animals seen and those shot." Reference to the map facing page 358 of the (op. cit.) report reveals that on the 15th and 16th, camps were made by Beaumont in Gap Valley, each 7-3/4 miles northeast of Cape Brevoort, one camp on either side of the 82° line, and separated from each other by a distance of only 2-1/4 air line miles or 4-1/2 miles march according to his journal.

These several data, then, are the bases for designating the type locality of M. e. polaris, in the way that I have stated it at the beginning of this account of the subspecies.

The light-colored upper parts and more intensely yellow underparts well differentiate this subspecies from arctica or semplei. Intergradation is suggested by a skin, no. 1462, Copenhagen Zoological Museum, from Axel Heibergs Land, the color of the underparts of which agrees with that of specimens from Greenland. Also the color of the upper parts is decidedly nearer that of animals from Greenland than to that of specimens from Ponds Inlet, Tulican and Gifford River. No other specimens west or south of Greenland suggest intergradation. In Greenland itself, one adult, a female from Turner Sund, East Greenland, has the underparts no more yellowish than in some specimens from Melville Peninsula. This female is darker on the back than any one of the other 10 specimens from Greenland in summer pelage examined at the same time, but even so is not so dark colored as animals from Baffin Island or other islands to the west of Greenland.

The final summation of information about this subspecies would have been more precise if I had been able to have actually in hand, at the time of writing, specimens preserved in the Copenhagen Zoological Museum. The war made it impractical to secure the loan of these as previously planned. Even so, the measurements and notes on color that I obtained from this material, in 1937, in Copenhagen, suffice to prove that the subspecies polaris is well set off in color from the other American subspecies of Mustela erminea.

The best material of this subspecies is in the University Zoological Museum at Copenhagen, Denmark.

Specimens examined.—Total number, 35, arranged by locality from the western end of the north coast of Greenland, eastward and then southward down the east coast. Unless otherwise indicated, specimens are in the Universitetets Zoologisk Museum, Købnhavn, Danmark.

Gap Valley, 7-1/4 mi. NE Cape Brevoort, 82° N, 59° 20´ W, 1 (British Mus.); Dragon Point, 1; Danmarks Havn (Fjeldene ved Baadskjeret, 1; lille Fjeld, 1; Lyservig, 1; harefjeldets, 4; Rypefjeldet, 1; Baadskjeret, 1; Danmarkshavn, 3) 12; Christians Havn, 1 (not found on map); Shannon Island, 4; Germania Havn, 2; Claveringoen, 1; Carls Havn, 1; Myggbukta, 2 (British Mus.); Ymer[s] Island, 2 (Mus. Comp. Zool.); Kap Hoegh, Jamesonsland, 1 (Berlin Zool. Mus.); Scoresby Sund, 3; Turner Sund, 4.

Mustela erminea semplei Sutton and Hamilton

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela arctica semplei Sutton and Hamilton, Ann. Carnegie Mus., 21:79, February 13, 1932.

Mustela arctica labiata Degerbøl, Rept. 5th Thule Exped., 2 (no. 4):25, 1935, type from Malugsitaq, Melville Peninsula, Canada.

Mustela erminea semplei, Hall, Journ. Mamm., 26:179, July 19, 1945.

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Type.—Male, subadult, skull and skin; no. 6470, Carnegie Mus.; Coral Inlet, South Bay, Southampton Island, Canada; October 8, 1929; obtained by George Miksch Sutton, original no. 3M.

The skull has two holes in it: one is immediately above the left canine, and the other (2 × 5.5 mm.) is 3 millimeters to the left of the median line at the juncture of the frontal and parietal bones. From this last mentioned hole a fracture extends back halfway to the lambdoidal crest. The tip of the left upper canine is broken off. Otherwise the skull is complete, and the teeth all are present and entire. The skin is well made and in fresh white winter pelage except for a trace of the old brown summer pelage on the back, on the tail, on the anterior borders of the ears, and in a spot 11 mm. long and 8 mm. wide on the nose.

Range.—Baffin and Southampton islands, Melville Peninsula and west side of Hudsons Bay as far south as Eskimo Point. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. arctica, in that, in males, hind foot less than 44 and basilar length less than 41 and in that females average smaller, their skulls being only about 10 per cent lighter; from M. e. polaris in darker upper parts (Raw Umber rather than Buckthorn Brown) and less-intensely-colored underparts that are Sulphur Yellow, Colonial Buff or Primrose Yellow rather than Buff Yellow, and in lesser size in the same fashion as from arctica; from M. e. richardsonii, of both sexes, in that proximal two-thirds of under side of tail colored same as underparts rather than same as upper parts and by least interorbital breadth amounting to more, instead of less, than distance between glenoid fossa and posterior border of external auditory meatus.

Description.—Size.—Male: Ten adults and subadults, from Southampton Island, yield average and extreme measurements as follows: Total length, 282 (267-318); length of tail, 77 (59-87); length of hind foot, 40 (38-43).

Female: Four subadults from Southampton Island yield average and extreme measurements as follows: Total length, 271 (256-288); length of tail, 71 (69-74); length of hind foot, 35 (33-38).

Color.—As described in M. e. arctica except that least width of color of underparts averaging, in 7 males, 59 (45-81) per cent of greatest width of color of upper parts. Black tip of tail in 19 male topotypes averaging 72 (64-83) mm. which is 91 (75-122) per cent of length of tail-vertebrae.

Skull.—Male (based on 2 adults and 10 subadults from Southampton Island): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 2.0 (in one subadult) grams; basilar length, 37.5 (35.7-39.9); length of tooth-rows more than length of tympanic bulla; breadth of rostrum more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen.

Female (based on 1 adult and 4 subadults from Southampton Island): See measurements and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 1.35 (in one adult) grams; basilar length, 34.2; breadth of rostrum more than 30 per cent of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more or less than (approximately same as) distance between last upper molar and jugular foramen.

In comparison with richardsonii, the skulls of males averaged smaller in every measurement taken except breadth of rostrum and interorbital breadth which are more, and zygomatic breadth and length of inner lobe of M1 which are approximately the same; skull about 20 per cent lighter; in relation to basilar length, preorbital region longer and broader in every part measured. Female averages larger, in every part measured; 23 per cent heavier; in relation to basilar length, every other measurement more. It is noteworthy that the skull of the male is smaller and the skull of the female larger than in richardsonii.

Differences from arctica are: Size less, in each sex; males about 40 per cent and females 10 per cent lighter; in males, skull more rounded in outline as viewed from above because zygomatic arches arise less abruptly from skull; in males tympanic bullae do not project so far ventrally from squamosal floor of braincase; with these exceptions, skull of semplei can be said to be a smaller edition of that of arctica.

From polaris, semplei differs, cranially, in the same way as from arctica.

Remarks.—There is a slight increase in size of ermines toward the north which probably is the result of intergradation between semplei and arctica. Specimens from the northern part of Baffin Island are larger than those from farther south. Specimens from the mainland west of Southampton Island may owe their smaller (than in arctica) size to intergradation with richardsonii almost as much as to intergradation with semplei.

Degerbøl's name Mustela arctica labiata was applied to specimens, which to me are indistinguishable from topotypes of Mustela arctica semplei, which latter name has three years priority. Degerbøl (1935:34) states that Malugsitaq, Melville Peninsula, is the type locality. He did not designate a type specimen. Reference to his account (op. cit.:26) shows that he lists five specimens from the type locality, or more precisely as "Malugsitaq, Lyon Inlet. 5 summer skins. ♂ ♂ June-July 1922. P. F., CN. 2262-2266." On labels attached to these specimens, "Lyon Inlet" is replaced with "Melville Peninsula." On July 28, 1937, Degerbøl and I together examined these specimens in his laboratory. Because no. 2262 is first mentioned I regard it as the type. It is a juvenal male, skull and skin, no. 2262 (20.5 1931.8), Univ. Zool. Mus. Copenhagen, obtained in June or July of 1922 by Peter Freuchen whose original number was / s 2324. The specimen is one of 5 males taken at the same locality by the same collector and they bear identical data as to date. They look to be of the same litter for all are roughly of the same size and each retains milk teeth.

Additional females, with external measurements carefully taken, are much needed from Southampton Island, because the available females are insufficient to show the degree of sexual dimorphism. If the meager data available be accepted, the difference in size between the two sexes is less than in other subspecies. My own feeling is that a better sample of females would show the secondary sexual difference in size to be more than available data indicate.

Specimens examined.—Total number, 183, arranged from north to south by islands, or regions attached to the mainland, and from north to south in each region or island. Unless otherwise indicated, specimens are in the Zoological Museum, University of Copenhagen, Denmark.

Baffin Island. Pond[s] Inlet, 8; (5[77]); Tulukan (sometimes spelled Tulukat), 6; Cape Eglinton, 1[7]; Gifford River, 2; Clyde, 3[86]; head of Cumberland Sound, 1[91]; Pangnirtung, 2[77]; Kingnait Fiord, 1[91]; Kikkulin Island, Cumberland Sound, 1[7]; Blacklead Island, Cumberland Gulf, 1; merely Cumberland Gulf, 1[7]; merely east Baffin Island, 34[7]; Cape Dorset, 2[2]; SW coast of Baffin Island, 1[75].

Melville Peninsula. Iglulik, 3; Pingerqalik, 2; Kingadjuaq, Amitsog, 3; Rae Isthmus, 3; Lyons Inlet, 13(9[2]); M[N?] alugsitaq, Lyon Inlet, 5; Itibdjeriang, 2; Repulse Bay, 27 (22[2], 2[19]); Drichetts Cove, Hurd Channel, 1[2]; Gore Bay, 1; Haviland Bay, 1; Cleveland Harbor, Frozen Strait, 1.

Southampton Island and adjacent islands. Danish Island, 11; Vansittart Island, 4. Southampton Island: Coral Inlet, 19 (1[77], 18[9]); Prairie Point, 1[9]; Munnimunnek Point, South Bay, 5[9]; Native Point, 1[9]; Ranger Rim, 1[9]; Koodloatok (not found on map), 1[77]; merely Southampton Island, 1[77]; Gore Bay, 1[2]; Fox Channel, 2[2].

Mainland to west of Southampton Island. Cape Fullerton, 3 (1[77], 2[2]); Chesterfield Inlet, 4 (1[77], 1[9]); Tavane, 1[77]; N of Wagner Inlet, 1; Eskimo Point, 1[86].

Mustela erminea kadiacensis (Merriam)

Ermine

Plates 2, 3, 4, 9, 10 and 11

[Putorius arcticus] subspecies kadiacensis Merriam, N. Amer. Fauna, 11:16, June 30, 1896.

Putorius kadiacensis, Preble, Proc. Biol. Soc. Washington, 12:169, August 10, 1898.

Mustela kadiacensis, Miller, U. S. Nat. Mus. Bull., 79:97, December 31, 1912.

Mustela erminea kadiacensis, Hall, Journ. Mamm., 26:179, July 19, 1945.

Type.—Male, subadult, skull and skin; no. 65290, U. S. Nat. Mus., Biol. Surv. Coll.; Kodiak Island, Alaska; April 25, 1894; obtained by B. J. Bretherton, original no. 304.

The skull lacks the basioccipital, part of the basiphenoid, the occipital region on the right side and the posterior part of the right tympanic bulla. The third, upper, left incisor is missing. Otherwise the teeth all are present and entire.

The white, winter skin is only moderately well stuffed but in a good state of preservation. The spring coat is appearing along the back. This coat is visible at only two places unless the hair be parted when the new brown pelage, which is coming in, can be seen all along the midline of the back.

Range.—Kodiak Island, Alaska. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. arctica in hind foot less than 33 in females and in zygomatic breadth amounting to less, instead of more, than distance between last upper molar and jugular foramen irrespective of sex.

Description.—Size.—Male: One adult and 3 subadults yield average and extreme measurements as follows: Total length, 341 (318-360); length of tail, 93 (86-102); length of hind foot, 47 (44-49).

Female: An adult measures: Total length, 258; length of tail, 70; length of hind foot, 31.

Color.—As described in M. e. arctica, except that least width of color of underparts averaging 54 (40-83) per cent of greatest width of color of upper parts. Black tip of tail in 3 males in summer pelage averaging 80 (70-90) mm. which is 85 (69-96) per cent of length of tail-vertebrae.

Skull.—Male (based on 2 adults): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight 3.1 grams; basilar length, 42.6 (42.1-43.2); length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes averaging more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus.

Female (based on one adult, no. 98042): See measurements and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 1.2 grams; basilar length, 33.0; length of tooth-rows more than length of tympanic bulla.

Comparison with arctica has been made in the account of that subspecies. Although richardsonii and kadiacensis are described as having the zygomatic breadth less than the distance between the last upper molar and jugular foramen, the zygomatic breadth is considerably more in kadiacensis than in richardsonii; consequently the two dimensions are more nearly equal than in richardsonii. Except for being slightly narrower, the skull of kadiacensis is only a slightly smaller edition of that of arctica.

Remarks.—When naming the weasel from the mainland of Alaska as new, under the name Putorius arcticus, Merriam (1896:16) wrote: "A small form of arcticus occurs on Kadiak Island. . . . It is probably worthy of recognition as subspecies kadiacensis." The informality of this description possibly was in part due to the describer's recognition of the fact that the degree of difference between arcticus and the insular kadiacensis was slight. Specimens collected after Merriam proposed the name for the weasel of Kodiak Island show the animal there to be less different from arctica of the adjacent mainland than he thought; small size is the most pro nounced distinction of kadiacensis and Merriam's male type specimen is smaller than any of the five additional males saved from Kodiak Island since that time. Even so the differences fully warrant subspecific recognition, in my opinion, although kadiacensis is not a strongly differentiated race. More adult females are needed to ascertain the norm of form and size for that sex. If the one female known is typical, the difference from arctica is more pronounced in females than in males. The lesser size of kadiacensis can hardly be credited entirely to the effect of insularity, for animals from the southern part of the mainland, on Kenai Peninsula for example, are smaller than those from central and northern Alaska and provide evidence of intergradation of a sort between kadiacensis and arctica.

Specimens examined.—Total number, 9, all from Kodiak Island, Alaska, and unless otherwise indicated in the U. S. National Museum.

Karluk, 1 (Stanford Univ.); Kodiak, 7; Kodiak Island, 1 (Field Mus. Nat. Hist.).

Mustela erminea richardsonii Bonaparte

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela richardsonii Bonaparte, Charlesworth's Mag. Nat. Hist., 2:38, 1838.

Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part).

Putorius richardsonii, Baird, Mamm. N. Amer., p. 164, 1858 (part-Halifax, N. S.).

Putorius (Gale) erminea, Coues, Fur-bearing animals, p. 109, 1877 (part).

Putorius richardsoni, Bangs, Proc. Biol. Soc. Washington, 10:16, February 25, 1896.

Putorius cicognani richardsoni, Merriam, N. Amer. Fauna, 11:11, June 30, 1896.

Putorius (Arctogale) cicognanii cicognanii, Bangs, Proc. New England Zoöl. Club, 1:18, February 28, 1899.

Putorius microtis Allen, Bull. Amer. Mus. Nat. Hist., 19:563, October 10, 1903. Type from Shesley, British Columbia.

Putorius arcticus imperii Barrett-Hamilton, Ann. and Mag. Nat. Hist., 13(ser. 7):392, May, 1904. Type from Fort Simpson, Mackenzie, Canada.

Putorius cicognanii richardsoni, Preble, N. Amer. Fauna, 27:231, October 26, 1908.

Mustela microtis, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912.

Mustela cicognanii mortigena Bangs, Bull. Mus. Comp. Zoöl., 54:511, July, 1913. Type from Bay St. George, Newfoundland.

Mustela cicognanii, Sheldon, Journ. Mamm., 13:201, August 9, 1932.

Mustela cicognanii richardsonii, Miller, U. S. Nat. Mus. Bull., 79:95, December 31, 1912; Hall, Univ. California Publ. Zoöl., 40:368, November 5, 1934.

Mustela cicognanii cicognanii, Hall, Canadian Field-Nat., 52:108, October, 1938.

Mustela erminea richardsonii, Hall, Journ. Mamm., 26:77, February 27, 1945; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.—Male, age unknown, skin; no. 43.3.3.4, British Museum of Natural History; probably from Fort Franklin, Canada; presented to British Museum on or before March 3, 1843; may be the type.

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In September, 1937, when I searched in the British Museum for the skull, I found no trace of it nor mention of it in catalogues. The skin is in white, winter pelage, mounted on a pedestal. See under remarks for Mustela e. cicognanii for reasons for and reasons against regarding this specimen as the holotype.

Range.—Hudsonian and Canadian life-zones of the greater part of Canada from the Atlantic to the Pacific. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. arctica, polaris, semplei and haidarum, in both sexes, by proximal two-thirds of under side of tail colored same as upper parts rather than same as underparts, and interorbital breadth less, rather than not less, than distance between glenoid fossa and posterior border of external auditory meatus; from M. e. bangsi, in that, in both sexes, least width of color of underparts averages two-fifths rather than about a third of greatest width of color of upper parts, and in that skulls of males are a fourth heavier, basilar length averaging more than 40; from M. e. cicognanii, in both sexes, in that least width of color of underparts averages two-fifths instead of less than a third of greatest width of color of upper parts, in females by 20 per cent heavier skull (1.1 versus 0.92), in males by skull more, rather than less, than 1.9 grams, and basilar length more, instead of less, than 38; from M. e. invicta, in males, by skull more, instead of less, than 1.9 grams; mastoid breadth more, instead of less, than 19.9 mm.; depth of skull at anterior margin of braincase more, instead of less, than 12.4 mm.; in females, by same measurement of depth more, instead of less, than 10.1, and weight of skull averaging more, instead of less, than one gram; from M. e. fallenda in both sexes upper lips white rather than brown, in males, hind foot more than 41, basilar length more than 38.3, in females hind foot more than 29, basilar length more than 31.4, and breadth of rostrum amounting to less, instead of more, than 30 per cent of basilar length; from M. e. alascensis in males in that black tip of tail more than 43, total length more than 320, tympanic bullae more than 14 and longer than tooth-row rather than less than 14 mm. and sometimes shorter than tooth-row, females not individually distinguishable.

Description.—Size.—Male: Four adults (Fort Franklin, Fort Simpson, Mts. W Fort Nelson, and Govt. Hay Camp, Wood Buffalo Park) yield average and respective measurements as follows: Total length, 331 average (340, 325, 330, 328); length of tail, 93 (102, 91, 93, 87); length of hind foot, 45 (48, 43, 45, 44). Weight of 4 adults from the Belcher Islands is 175 (135-180) grams. Of 10 subadults from Belcher Islands it is 119 (92-137) grams.

Female: Three adults from Great Slave Lake (Willow River, Fairchild Point, and Fort Resolution) yield average and respective measurements as follows: Total length, 252 (237, 238, 282); length of tail, 69 (63, 60, 85); length of hind foot, 32 (31, 32, 34). Corresponding, average measurements for three adults from Glacier Lake are 240, 60, 32 and for 3 adults from the Athabasca Delta, 243, 65, 30. Weight of 8 subadults from the Belcher Islands is 69 (64-78) grams. Weight of adults would be more.

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Color.—Winter pelage all white except tip of tail. Summer pelage with upper parts uniform in color and darker (16n) than Raw Umber, and about tones 3 to 4 of Chocolate of Oberthür and Dauthenay, pl. 343. Underparts Sulphur Yellow, Colonial Buff, or Primrose Yellow, often nearly white on chin and insides of forelegs; color of underparts extends narrowly over upper lips, distally on posterior sides of forelegs onto antipalmar faces of toes and sometimes over most of antipalmar surfaces of forefeet, on medial sides of hind legs to a point between knee and ankle but reappears on antiplantar faces of toes and in some individuals is narrowly continuous onto toes. Least width of color of underparts averaging, in a series of 12 males from the Athabasca Lake Region, 40 (25-54) per cent of greatest width of color of upper parts. Black tip of tail averaging 56 (45-63) mm. in 5 adult males from same region and thus 60 (48-70) per cent of length of tail-vertebrae.

From arctica, polaris, semplei and kadiacensis, richardsonii differs in: Color darker; ventral side of tail same color as upper parts; light-colored underparts a fifth narrower; black tip of tail by actual measurement a fifth shorter and averaging less than two-thirds rather than more than four-fifths of length of tail-vertebrae. From cicognanii, richardsonii differs in that the underparts are a fourth wider and in some specimens more brightly colored. The width of the underparts is likewise a fourth more than in bangsi. In invicta the underparts are not so brightly colored as in some specimens of richardsonii. From fallenda, richardsonii differs in that the upper parts often are lighter colored, upper lips white rather than colored like upper parts, and underparts as wide again. In comparison with alascensis, the black tip of the tail averages three-fifths rather than a half of length of tail-vertebrae.

Skull.—Male (based on 6 adults from 3 miles south of Big Island, Great Slave Lake): See measurements and plates 2-4; weight, 2.5 (2.1-2.9) grams; basilar length, 40.9 (39.6-43.7); length of tooth-rows less than length of tympanic bulla; breadth of rostrum measured across lacrimal processes less than a third of basilar length; interorbital breadth less than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth less than distance between last upper molar and jugular foramen.

Female (based on 4 adults: from Willow River, 1; Fort Resolution, 1; Athabasca Delta, 2; and 2 subadults, one from 3 mi. S Big Island and one from 15 mi. above Smith Landing): See measurements and plates 9-11; weight, 1.1 (0.9-1.4) grams; basilar length, 33.1 (31.5-34.2); length of tooth-rows less than length of tympanic bulla; breadth of rostrum less than 30 per cent of basilar length; interorbital breadth less than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth less than distance between last upper molar and jugular foramen.

The skull of the female averages 56 per cent lighter than that of the male.

Comparison of the skull with that of arctica, polaris, semplei, kadiacensis, haidarum, cicognanii, bangsi, invicta, fallenda, and alascensis is made in the accounts of those subspecies.

Remarks.—M. e. richardsonii has the most extensive geographic range of any American race of erminea, is centrally located with respect to the other races, is more abundantly represented by study specimens in zoölogical collections than any other race, and is a sort of average for the species as a whole in most structural features. Therefore richardsonii is used as a standard of comparison and accordingly is more fully described than any one of the other races each of which by reference to richardsonii is described in comparative fashion. This comparative description has the virtue of more clearly indicating differences between subspecies and also makes for brevity.

John Richardson, Bernard R. Ross, and names of their companions, as written on the labels of the older specimens recall to the student's mind early explorations of the north country. Edward A. Preble obtained important specimens at several places and in recent years J. Kenneth Doutt and G. G. Goodwin have made the reviser's work easier by preparing specimens in series from areas not previously well represented.

The nomenclatural history of this subspecies begins with references in the literature that identify the animal as the Old World species, Mustela erminea—an identification which the study here reported upon shows to have been correct in the specific, although not in the subspecific, sense. Richardson, for example, in his "Fauna Boreali-Americana" published in 1829 so identified the animal. In 1838, Bonaparte, basing his description on Richardson's account of 1829, proposed the new name richardsonii. Richardson himself, the following year in the "Zoology of Beechey's Voyage," accepted Bonaparte's name and it has been applied to the animal in the central part of the northern timber-belt of North America ever since, except as authors used the name Mustela erminea in the belief that richardsonii was not distinct from erminea.

The north and south boundaries of the range assigned to richardsonii varied according to the notions of the particular writer who was employing the name. Until Merriam in 1896 named arctica as distinct, animals from the far north were generally included under the name richardsonii along with populations to which the latter name now is applied. Because richardsonii grades gradually into the smaller cicognanii of more southern occurrence the boundary between the two has been set farther north by one writer and farther south by another, depending probably upon what the writer felt was the halfway point in size. This point of course depended upon the samples selected as typical of richardsonii on the north and cicognanii on the south. Because Bangs, in 1896, took as representative of richardsonii the far northern and hence large-sized animals (now separated as M. e. arctica), his halfway point in size between them and the small cicognanii of New England naturally fell farther north than it would have had he used as representative of richardsonii specimens from places south of the range of arctica.

In 1903 J. A. Allen proposed the name Putorius microtis for a specimen from Shesley, northwestern British Columbia, a place approximately 50 miles northwest of Telegraph Creek. Considering the great disparity in size between this one specimen and the other larger specimens of normal size, from the general region, available to Allen at that time, it is not surprising that he thought two full species were represented. In 1943 when G. G. Goodwin called to my attention two males, as small as the type of microtis and taken by him approximately 300 miles east of Shesley, in the valley between the Musqwa and Prophet rivers, I for a second time examined all available specimens and data with the possibility in mind that microtis was a species or subspecies distinct from M. e. richardsonii, but again concluded that only one subspecies was involved because no character except size was found to distinguish the large from the small individuals of a given sex and there are, preserved from northern British Columbia, individuals of intermediate size. Putorius microtis Allen seems to have been based on an individual of M. e. richardsonii near the lower limit of size for that subspecies and microtis is regarded as a synonym.

Barrett-Hamilton in 1904 named the animal at "Fort Simpson, British Columbia" Putorius arcticus imperii. Preble (1908:232) pointed out that Fort Simpson on the Mackenzie undoubtedly was the place intended, and arranged imperii as a synonym of M. e. richardsonii. The type specimen of imperii was stated to have been received from B. M. Ross who is known to have collected specimens, including specimens of this species (now in U. S. Nat. Mus.), at Fort Simpson on the Mackenzie. I know of no Fort Simpson in British Columbia. If, as seems improbable, Port Simpson, British Columbia, was the place that Barrett-Hamilton intended to designate (where so far as I know Ross did not collect), the name imperii still would seem to be a synonym of richardsonii because richardsonii seems to be the race of weasel at Port Simpson. In proposing the name Putorius arcticus imperii, Barrett-Hamilton stressed that the weasel, which he was naming, was a subspecies of P. arcticus, gave characters which applied perfectly to richardsonii but made no reference to richardsonii. Barrett-Hamilton did not refer to richardsonii possibly because he relied on Merriam's classification of 1896 wherein richardsonii is treated as a species distinct from arctica. Merriam, it will be remembered, held that slight degree of morphological difference rather than intergradation was the criterion for subspecies. Although I have no record of having examined the type specimen of imperii I have but little hesitancy in treating it as a synonym, and would have no hesitancy at all in so doing if the type was certainly known to have been obtained at Fort Simpson on the Mackenzie.

The name Mustela cicognanii mortigena Bangs, 1913, proposed for the ermine of Newfoundland, is placed as a synonym of richardsonii only after repeated, detailed comparisons. In advance of study I supposed that the isolation of the ermine, in Newfoundland, had contributed to its differentiation, which, however, the original describer, Bangs, indicated was slight. Bangs was a careful worker and I am confident that the differences he described really existed between his specimens. Material more nearly adequate than he had from the mainland, shows the males, so far as my measurements and comparisons go, to be in nowise different from those in Newfoundland. Females in Newfoundland may have, on the average, slightly longer hind feet than on the opposite mainland but I am not certain that they do and even if there is a slight difference in this regard as suggested by available data, I think it insufficient basis, alone, for according subspecific status to the insular animal.

The name richardsonii was based by Bonaparte on Richardson's description which in turn was drawn from a specimen taken at Fort Franklin, that thus becomes the type locality. It is fortunate that Preble, in 1903, succeeded in taking specimens there because the place is near the belt of intergradation between arctica and richardsonii. Of Preble's two adult males (see Preble, 1908:232) I have examined no. 133847, which is in transitional pelage and therefore gives no clue in so far as coloration is concerned, as to affinities with arctica versus richardsonii. Specimens in the summer pelage are much to be desired from Fort Franklin. Regardless of what their coloration may be, specimen no. 133847, in external measurements and most certainly in cranial features is of the race to the south and not the race that Merriam named arctica. Because all specimens from localities to the south of Fort Franklin likewise differ from arctica of the barren grounds, considerable additional confidence is felt in allocating the name richardsonii to the animal which ranges from Fort Franklin southward rather than to the one, here designated arctica, that occurs to the northward of Fort Franklin.

Although in most structural features richardsonii is a sort of average for the American races of the species, it is the extreme in high degree of sexual dimorphism. The difference in size between the males and females is greater than in any other race except possibly M. e. kadiacensis in which so little is known of the female that the difference between the two sexes cannot be accurately judged. It will aid in understanding the high degree of secondary sexual difference in richardsonii to visualize two kinds of weasels distributed over the northern half of the continent, thinking now of the geographic area in America occupied by the whole species Mustela erminea of which the subspecies richardsonii is only a part. One of the two kinds of weasel is the male ermine and the other the female. The decrease in size of the male, as measured by the weight of the skull, is in the ratio of 7 in the north to 2 in the south. This decrease is gradual whereas the corresponding decrease from 3 to 1 in the female is not gradual; half of the decrease in the female occurs in the short north to south distance comprised in the belt of intergradation, along the northern boundary of richardsonii, between it and arctica. As a result richardsonii is composed of females with medium sized skulls and males with relatively large skulls, the ratio by weight being approximately 5 to 2. The disproportion in races of ermines both to the north and to the south is less. Actually in the north (arctica) the approximate ratio by weight is 2-1/3:1; in richardsonii, 2-1/2:1; in the south (muricus), 1-2/5:1. Indicated in still another way in richardsonii the skull of the female is 56 per cent lighter than that of the male and the skull of the male is 127 per cent heavier than that of the female. Intergradation with races whose ranges border on that of richardsonii is complete. On the northern boundary of the range of richardsonii along the western shore of Hudsons Bay for perhaps a hundred miles north of Eskimo Point, there are intergrades with arctica. As judged by their lesser size, individuals of this population are influenced by the semplei-stock. Otherwise, intergradation on the northern boundary, with arctica, is abrupt whereas intergradation at the south, between richardsonii and cicognanii, is gradual. Intergradation is similarly gradual between richardsonii on the one hand and bangsi and invicta on the other. By speaking of the intergradation as abrupt, it is intended, in this instance, to indicate that in a relatively narrow belt, between the geographic ranges of arctica and richardsonii, ermines intermediate in color-pattern, shape of skull, and size, bridge the gap between the ermine of the tundra (arctica) and that in the forest belt (richardsonii). It may be added that the degree of difference between the two subspecies just mentioned is approximately twice as much as between richardsonii and cicognanii. The intergradation between cicognanii and richardsonii is gradual. By gradual it is meant that the change from one kind to the other is achieved in a wider area where ermines from locality A do not differ appreciably from those taken at, say, locality B, 50 miles farther south, although ermines from A and those from a third locality, C, say, 130 miles south, clearly show differences indicative of geographic variation.

Specimens examined.—Total number, 1035, as follows. Arranged alphabetically by provinces and districts and from north to south in each province or district. Unless otherwise indicated, specimens are in the United States National Museum.

Alberta. 15 mi. above Smith Landing, 2; Fort Smith, 2 (1[77]); Smith Landing, 2; LaButte, Fitzgerald, 1[77]; Egg Lake, 15 mi. NW Ft. Chippewyan, 4 (2[75]); Lobstick Island, near Ft. Chippewyan, 1; Athabasca Delta, 9 mi. above mouth of main branch, 1; Athabasca Delta, Long Creek, 1 mi. W of main branch, 2; Ft. Chippewyan, 1; Peace Point, 1[75]; 18 mi. below Peace Point, 1; Embarass River, 7 (4[75]); Athabasca River, 1[2]; Ft. McMurray, 1; Athabasca River, Middle Rapid, 2; 60 mi. above Grand Rapids, 1; Boiler Rapid, 1; Entrance, 3[2]; St. Albert, 2.

British Columbia. Fort Halket, 1; Shesley, 1[2]; Dorothy Lake, Mts. W of Ft. Nelson, 4000 ft., 3[2]; valley between Musqwa and Prophet rivers, 3800 ft., SW of Ft. Nelson, 2[2]; Sikanni Chief Riv., 1; Telegraph Creek, 7 (6[2]); head of Bad River, 2350 ft., on lake, 1; Six Mile, 5[74]; Tuchodi Lake, 2[2]; Iskoot River, 2[14]; Level Mtn., 1[2]; head of Tatletuey Lake, 12 mi. W Thudade Lake, 2; Robb Lake District, 5[2]; Ft. Grahame, 12 (2[77]); Sustut Mts., on trib. Sustu Riv., 25 mi. SE Thudade Lake, 2; Laurier Pass, 1; Omineca Mts., 1[85]; Point Creek and Clearwater River, 2; Kispiox Valley, 23 mi. N Hazelton, 5[74]; Hazelton, 3[77]; NW arm Tacla Lake, 7; N end Babine Lake, 1; Pt. Simpson, 1; Metlakatla, 1; Stuart Lake, 27; S Fk. Salmon Riv., 1[77]; mouth Salmon Riv., 1[77]; Vanderhoof, 4[77]; Wistaria P. O., near Burns Lake, 1[77]; Kruger Lake, 9[74]; Indianpoint Lake, 23[74]; Quesnel, 1; Ahbau Lake, 3[74]; Isaacs Lake, 6[74]; Beaver Pass, 56[74]; Lightning Creek, 54[74]; LaFontaine, 16[74]; Barkerville, 1[74]; Barkerville District, 34[74]; Swift River, 27[74]; Cunningham Creek, 34[74]; Itcha Mts., 1[31]; Anahim Lake, 1[74]; Chezacut Lake, 8[31]; Kleena Kleene, 18[74]; 158 mi. House (Cariboo on labels), 3[60]; Rivers Inlet, 6 (5[94]; 1[77]); Horse Lake, 4[22]; Kingcome Inlet, 8[77]; Loughborough Inlet, 7[77]; McGillivary Creek, 1; Camel Back, Pemberton Meadows, 1[31]; Arrow Rapids, mainland opposite Stuart Island, 1[77]; Butte Inlet, 9[77]; Green Lake, 1[31]; Mt. Whistler, 1[86]; Alta Lake, 2 (1[31]; 1[21]); Mons, 1[31].

Keewatin. Foot of Baker Lake, 1.

Labrador. Okak, 3[75]; Nain, 22 (11[75]; 11[60]); Hopedale, 24[75]; Kippokak Bay, 7[75]; Ailik, 1; Makkovik, 26[75]; Labrador, 55° N, 3; Hamilton Inlet, 2[75]; NW River Post, interior Labrador, 5[1]; Cartwright, 5; Paradise, 12; Sandwich Bay (Muddy Bay, 6; North River, 6), 12; Battle Harbor, 1[7]; St. Marys River, 3[7]; Black Bay, 16 (15[75]; 1[76]); Lanceau Loup, 17 (1[75]).

Mackenzie. Ft. Franklin, 1[2]; Ft. Rae, 12; Fairchild Point, 6[9]; Fort Simpson, 10 (2[2]); Hot Springs (61°, 125°), 1[2]; Willow River, near Ft. Providence, 1; 35 mi. N Big Island, 7; Big Island, 9; 3 mi. S Big Island, 7; Ft. Resolution, 9; 100 mi. N Ft. Smith, 2; 75 mi. NW Ft. Smith, 1; Ft. Liard, 2; Sucker Creek, 4[77]; Govt. Hay Camp, Wood Buffalo Park, 2[77].

Manitoba. Egg Is., Rabbit Point, 1; Ft. Churchill, 1; Ft. York, W Hudsons Bay 57° N, 1[7]; Oxford House, 11; Gypsumville, 1[86]; Lake St. Martin.

New Brunswick. Restigouche County: Bird Bait, north Camp, 6 mi. NE Nictau Lake, 2[59]; Red Brook, Tobique River, 1[59]. Victoria County: Trousers Lake, 3[2]. Glouchester County: Youghall, 1[77]; Miramichi Road, 15 mi. from Bathurst, 13[77]. York County: Scotch Lake, 2.

Newfoundland. Nicholsville, 3[75]; Bay St. George, 48 (26[75]; 2[7]; 1[9]); Codroy, 9 (7[75]; 2[60]).

Nova Scotia. Victoria County: Cape North, 2[77]. Inverness County: Fizzleton, 3[77]. Richmond County: St. Peters, 1[77]. Pictou County: Glengary, 1[4]. Guysborough County: East Roman Valley, 5[77]. Kings County: Wolfville, 5 (3[74], 2[77]); near Wolfville, 1[77]. Halifax County: Hammond Plains, 1. Annapolis County: Annapolis Royal, 1. Digby County: Digby, 3. No locality more definite than Nova Scotia, 3.

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Ontario. Severn River, 1[77]; R. C. Mission, Yellow Creek, near mouth of Albany, 2[86]; Ft. Albany, 4; Charlton Island, 1; Moose Factory, 10 (7[9]; 3[77]); Abitibi, 1[4].

Quebec. Fort Chimo, 10[77]; Ungava Forks, 1; Belcher Islands, Hudsons Bay (Tukarak Island, 29; Eskimo Harbor, 2; Innetalling Island, 1; S tip Gibson Peninsula, 2; Flaherty Island, 1), 35[9]; Cairn Island, Richmond Gulf, 2[9]; Manitounuk Sound, 4[9]; about 15 mi. S Great Whale River, 1[9]; Ft. George, 1[9]; Charlton Island, 1[9]; Waswonaby Post, 1[77]; Mistassinnay Post, 3[77]; Godbout, 36; Mt. Albert, 7 (4[78]; 3[2]); St. Anne River, 1500 ft., 1[77]; Ste. Anne des Monts, 3[2]; "Federal Mine," 1[77]; Berry Mountain Camp, 1[77]; Berry Mountain Brook, 1[2]; Cascapedia River (Middle Camp, 2; Tracadie, 2; Square Forks, 1), 5[2].

Saskatchewan. Poplar Point, Athabasca Lake, 1[75]; Fair Point, Athabasca Lake, 1[75]; Emma Lake, 1[74]; Harper Lake, 2[77]; Livelong, 3[55]; Fairholme, 2[74]; Touchwood Hills, 2[7]; Indian Head, 1[86].

Yukon. Hoole Canyon, 1; Teslin Lake (30 mi. N of, 1; Lake itself, 1; "near" the lake, 1; Mts. "near," 2; Snowden Mts., 2; Teslin Post, 2; Eagle Bay, 1; Morley Bay, 2; Nisutlin River, 1; Nisutlin Flats, 2; Wolf River, 1; Wolf Lake, 5), 21[77].

Mustela erminea cicognanii Bonaparte

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela cigognanii [sic.] Bonaparte, Charlesworth's Mag. Nat. Hist., 2:37, 1838.

Putorius vulgaris, Emmons, Quadrupeds of Massachusetts, p. 44, 1840.

Mustela pusilla DeKay, Zool. of New York, Pt. 1, Mammalia, p. 34, pl. 14, fig. 1, 1842. Type from New York State.

Putorius pusillus, Audubon and Bachman, Vivip. Quadrupeds of N. Amer., 2:100, pl. 64, 1851 (pl. 1846) and erroneously labeled Mustela fusea, as pointed out on page 102 of text.

Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858.

Putorius richardsoni cicognani, Bangs, Proc. Biol. Soc. Washington, 10; 18, figs. 4, 4a of pls. 1 and 2, and pl. 3, figs. 2, 2a, February 25, 1896 (part).

Putorius cicognani, Merriam, N. Amer. Fauna, 11:10, pl. 2, figs. 3, 3a, 4, 4a and pl. 5, figs. 2, 2a, June 30, 1896.

Mustela cicognanii cicognanii, Miller, U. S. Nat. Mus. Bull., 79:95, December 31, 1912; Bishop, Journ. Mamm., 4:26, February 9, 1923.

Mustela cicognanii, Jackson, Journ. Mamm., 3:15, February 8, 1922.

Mustela erminea cicognanii, Hall, Journ. Mamm., 26:77, February 27, 1945; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.—No type specimen designated; type locality, eastern United States.

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The restriction of the type locality from the general region of northeastern North America, as given by Merriam (1896:10) to the less inclusive area of the eastern United States as earlier given by Bangs (1896:18) is supported by Bonaparte's remarks in connection with the proposal of the name cicognanii. He says (1838:37-38) "During my stay in the United States, I only saw a small species of Mustela, very common throughout the Union . . . ." This animal constituted basis for the name cicognanii which name, he points out, is bestowed in order that the Americans ". . . should have constantly under their eye, this very common little animal, as the perpetual memorial . . ." to the Italian Governmental representative ". . . who, for upwards of fourteen years had served, in diplomatic and commercial concerns, . . . two countries, . . . so different . . . as the Roman and the United States. . . ." Clearly he had in mind principally, if not exclusively, the animal of the United States.

Range.—Transition and higher life-zones of northeastern United States south to Connecticut, central Pennsylvania and extreme northeastern Ohio; in Quebec and Ontario westward from the latitude of central Maine to Lake Nipigon and Lake of the Woods. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. richardsonii of both sexes, in that least width of color of underparts averages less than a third rather than two-fifths of greatest width of color of upper parts, in males skull less, instead of more, than 1.9 grams and basilar length less than 38, in females by 16 per cent lighter skull (0.92 versus 1.1 grams); from M. e. bangsi, in males hind foot less instead of more than 40, linear measurements of skull averaging 11 per cent less (depth of skull at plane of molars 10.0 versus 11.4), in females averaging smaller, hind foot 30 versus 32 and depth of skull at plane of molars 8.6 versus 9.1.

Description.—Size.—Male. Seven adults and subadults from New York and Pennsylvania, yield average and extreme measurements as follows: Total length, 266 (240-295); length of tail, 74 (66-80); length of hind foot, 36 (33-39). Hamilton (1933:294) gives the weight of 31 adults from New York as 81 (66-105) grams.

Female: Twelve adults and subadults from Maine and the area south to central Pennsylvania, yield average and extreme measurements as follows: Total length, 243 (225-260); length of tail, 63 (55-72); length of hind foot, 29.8 (26-32). Hamilton (1933:294) gives the weight of 15 adults from New York as 54 (45-71) grams.

Color.—As described in Mustela erminea richardsonii except that underparts in summer Marguerite Yellow or even more whitish; least width of color of underparts averaging, in adult males from New York and Pennsylvania, 29 (27-32) per cent of greatest width of color of upper parts. Black tip of tail in same series averaging 42 (30-51) mm. which is 57 per cent of length of tail-vertebrae.

Skull.—Male (illustrated by 4 adults in table of cranial measurements, which see): See plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.5 (1.2-1.7) grams; basilar length, 35.7 (33.8-37.6).

Female (illustrated by adult and subadults recorded in table of cranial measurements, which see): See plates 9-11. As described in Mustela erminea richardsonii except that: Weight of 2 subadults, 0.92 (0.86-0.98) grams; basilar length, 32.4 (31.4-33.3).

The skull of the male, in linear measurements, is approximately 13 (12-16) per cent smaller and 40 per cent lighter than in M. e. richardsonii. In relation to the basilar length, the skull averages slightly narrower, slightly shallower as measured in the vertical plane touching the posterior borders of the last upper molars, and the preorbital part is slightly longer. In skulls of females of cicognanii, linear measurements average 3 (0-6) per cent less, the weight is 16 per cent less and the teeth are 5 per cent shorter. In relation to the basilar length, measurements of the skull are approximately the same or slightly less in cicognanii.

In comparison with bangsi, the male sex in linear measurements of the skull and teeth averages 11 per cent less than in bangsi from Aitkin, Minn., and 6 per cent less than in bangsi from Elk River, but in relation to the basilar length the preorbital region is larger. The weight is approximately a fourth less. In females the measurements average less, some being the same, and in relation to the basilar length, the bullae are shorter and the skull is shallower. The weight is about the same.

Remarks.—In January, 1838, in Charlesworth's Magazine of Natural History, C. L. Bonaparte proposed for three kinds of American weasels the names Mustela cicognanii, Mustela richardsonii and Mustela longicauda.

In this paper Bonaparte indicates that he previously had written (for his Iconografia della Fauna Italica ...) an account of Mustela cicognanii using this same name. Fasciola XXII of the Iconogr. d. Fauna Italica, presenting his account of Mustela, like the English paper was published in the year 1838. In his article in Charlesworth's Magazine, Bonaparte refers to his book published [used the past tense] in Rome but whether it actually appeared first I am unable to determine and hence am uncertain which of the two constitutes the original description.

Reference to the Italian account suggests as basis for the name M. cicognanii, (1) specimens possibly seen in the United States by Bonaparte, or (2) Godman's published account of the animal.

In the English publication, however, Bonaparte actually says that (1) he saw the small species in the Union [= United States]. Also, he (2) mentions his earlier written Italian account, (3) mentions that "all the [American?] naturalists" used the name M. vulgaris for this animal, (4) incidentally mentions Godman's account, and (5) in naming two other American species cites accounts of them by Richardson. Also, Bonaparte in this English article makes clear that when he wrote [not necessarily published] his Italian paper he did not know of the existence of two of the three American species.

In the register of mammals at the British Museum of Natural History, there appears:

43.3.3.3 Mustela longicauda Bonap N Amer. presented by Dr. J. Richardson
4 Mustela Richardsonii Bonap        "
5  "    Cicognanii Bonap          "

To the right of these entries there appears, in three lines, the notation: "The three specimens examined by Prince Canino on which he established the three species."

Every part of each of the above entries is in the hand writing of J. E. Gray, in charge of the collections from 1824 to 1840 and associated with them as Keeper until 1875. The three specimens are in good condition considering their age. The catalogue or register number shows, among other things, that they were entered in the register on March 3, 1843.

Questions which might occur to anyone are:

(1) Was there a type specimen of Mustela Cicognanii Bonaparte? If so is it no. 43.3.3.5?

(2) If there was no type specimen was there a type locality? If so what is it?

Among other things that may have bearing on these questions, are these: Bonaparte in Charlesworth's Magazine appears to base the two names Mustela Richardsonii and Mustela longicauda on Richardson's published account of Mustela erminea. At any rate immediately following each of the two names, Bonaparte writes "Nob. (M. erminea Rich. F. Bor. Amer.)." Bonaparte's other, first newly proposed name, Mustela Cicognanii, in Charlesworth's Magazine has following it only "Nob. North America," although in a paragraph above he did point out that this was the animal which all naturalists, at the time he was in America, considered as M. vulgaris.

Turning to Richardson's account (Fauna Boreali Americana, ... Quadrupeds, pp. 45-47. 1829) one finds that he recognized two species, M. vulgaris and M. erminea. Of the first he gives measurements "of an old female killed at Carlton House." Of the second species he distinguishes two varieties, the first represented by a specimen, of which he gives measurements, "killed at Fort Franklin, Great Bear Lake" and, the second variety "of a larger size, having a longer tail and longer fore-claws" he indicates the size of by giving measurements of a specimen taken "in the neighborhood of Carlton House."

The last variety is clearly the basis of Bonaparte's M. longicauda. The specimen from which Richardson took his measurements I have been unable to locate [no. 43.3.3.3 in the British Museum, appears to be another specimen, although of the same subspecies and provided by Richardson].

The first variety of Richardson's Mustela erminea, clearly is the basis of Bonaparte's M. Richardsonii. The specimen from which Richardson took his measurements may well be no. 43.3.3.4 now preserved in the British Museum of Natural History, but I could not be certain about this.

Richardson's M. vulgaris is accompanied by measurements of a female which I have ascertained to my full satisfaction is the identical specimen now bearing catalogue number 43.3.3.5 said by Gray to be the specimen on which Bonaparte based his name Mustela cicognanii.

Gray probably saw his guest, Bonaparte, at work on these weasels and Gray's own written indication perhaps should be accepted at its face value. I found only 4 Richardson specimens of North American weasel in the British Museum in 1937 and it is conceivable that Bonaparte, 100 years before, actually had at hand only one specimen each of two kinds and 2 specimens of the third. This I think is not an important consideration, though, for Gray says just which specimens did serve as basis for Bonaparte's names and there is only one specimen for each name according to Gray.

But I wonder if a type specimen can be made in this way? That is to say, after a name is published in a manner which makes it available, and if two or more specimens of the kind of animal involved, were, or may have been, available to the describer, can a person, even the author, himself, make a type specimen by saying that one particular specimen is beyond doubt the specimen on which a given name was established even though no particular specimen was designated in the original description? I incline to the view that a specimen so designated would at most be only a lectotype, unless it were a cotype.

However, if a holotype can be made by action such as Gray took, then (1) is no. 43.3.3.3 the type specimen of Mustela longicauda Bonaparte and, (2) is no. 43.3.3.4 the type specimen of Mustela Richardsonii Bonaparte?

Incidentally, Mustela longicauda Bonaparte whether based on no. 43.3.3.3 or on Richardson's account will continue in its present application. The same is true of Mustela richardsonii. If the basis of Mustela cicognanii Bonaparte [the diagnosis in the Iconografia d. Fauna Italica ... makes it clear that the name applies to the short-tailed species] was a weasel from the eastern United States or a description of a weasel or weasels from there, the name will continue in its present application. If, instead, the name is based on no. 43.3.3.3 (from Carlton House, Saskatchewan) or on Richardson's account of M. vulgaris, the name will apply to a different subspecies (now called richardsonii and richardsonii will fall as a synonym of cicognanii) and the ermine of the eastern United States will take the next available name. Bonaparte probably named (in manuscript at least) cicognanii before he ever saw the specimen in the British Museum. This is indicated by his statement in Charlesworth's Magazine (1838:37) that "I have now [Italics mine] found two [other] American species. . . ." Whereas the names richardsonii and longicauda are based on Richardson, the name cicognanii, even if it dates from the account in Charlesworth's Magazine, appears to have a composite basis composed at the very least of (1) animals seen by Bonaparte in the United States, and (2) those called vulgaris by some other authors. Conceivably the specimen no. 43.3.3.3 in the British Museum, was part of the basis. From the nature of the case it can be argued that there could be no type and that if someone should bring to light a specimen in, say, Philadelphia, bearing the notation "this is the specimen seen in the United States by Bonaparte" it would immediately become as important as the one in London. Any American weasel or weasels (then alive or preserved in a zoölogical collection) that Bonaparte saw in the United States probably were of the eastern United States. Bangs (1896:18-21), for one, previous to the present consideration of the name cicognanii, restricted it to the ermine of the eastern United States. Consequently, the name cicognanii, in the present account is applied to the ermine of the eastern United States. In my opinion there was and is no type. Almost certainly there was no type if the Fauna Italica appeared before the account in Charlesworth's Magazine did.

Specimens examined.—Total number, 172, arranged alphabetically by provinces and states, then (except where indication is given to the contrary) by counties from north to south within each state or province. Unless otherwise indicated, specimens are in the U. S. National Museum.

Connecticut. Windham County: S. Woodstock, Woodstock Lake, 1[2]. Hartford County: Windsor, 1[5]. New London County: Liberty Hill, 3[75].

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Maine. Aroostook County: Quimby, 1[75]; Ashland 2[75]. Piscataquis County: tableland on top of Mt. Katahdin, 1; Chimney Pond, 3; T. 5, R. 13, 3[5]; "vicinity of Chesnucook," 1[5]; T. 4, R. 13, 1[5]; Moosehead Lake, 7[75]; Grenville, 10 [75]; Barnard, 3 (1[86]). Penobscot County: South Twin Lake, 1[2]; Lincoln, 11 (7[1], 2[14], 2[50]). Franklin County: Seven Pond Township, 7[75]. Oxford County: Umbago Lake, 1[75]; Upton, 4[86]; Bethel, 1[75]. Hancock County: Bucksport, 17[75]; Naskeag, 1. Lincoln County: Booth Bay, 1[5].

Massachusetts. Middlesex County: Wilmington, 2; Burlington, 6 (1[75]); Worcester County: Cambridge, 5 (1[5], 3[75]); Sterling, 1[5]. Plymouth County: Middleboro, 7 (1[75]).

New Hampshire. Carroll County: Ossipee, 5. Rockingham County: Greenland, 1[76]. Cheshire County: Dublin, 1.

New York. St. Lawrence County: Ogdensburg, 1[74]. Franklin County: Malone, 1[58]. Lewis County: Locust Grove, 1. Warren County: Lake George, 1. Montgomery County: Amsterdam, 1. Albany County: Albany, 1[80]. Rensselaer County: Berlin, 2[2]; Schoharie, 1[2]. Thompkins County: Cascadilla Creek, Ithaca, 1[58]. Allegany County: Ford Brook, Wellsville, 1[58]. Ontario County: Phelps, 1[50]. Cattaraugus County: Cattaraugus, 1[5].

Ontario (localities locally north to south, then west to east). Thunder Bay Dist.: Grand Bay, Lake Nipigon, 5[86]; Macdiarmid, 2[86]; Oscar, 2[14]; 20 mi. SW Fort Williams, 1[76]; Michipicoten Island, 3[102]. Algoma Dist.: Michipicoten, 1; Franz, 1[74]; Pancake Bay, 2[77]. Parry Sound Dist.: French River, Georgia Bay, 1[2]; Seguin Falls, Twp. Montieth, 1[86]. Sudbury Dist.: Casselman, Rathbun Twp., 1[86]. Nipissing Dist.: Smoky Falls, near Kapuskasing, 4[86]; Franks Bay, Lake Nipissing, 1[86]. Haliburton County: Gooderham, 1[60]. Simcoe County: Orillia, 1[2]; no locality more definite than county, 1[60]. Carleton County: Britannia, 5 mi. W Ottawa, 1[77]; Ottawa, 1[77]; Constant Bay, NE? of Ottawa, 1[77]. Wellington County: Mt. Forest, 2[75]; Guelph, 1[31]. Addington County: Buckshot Lake, Abinger Twp., 1[86]. Fontenac County: Clear Lake, Arden, 1[77].

Pennsylvania (by counties from west to east). Crawford County: North Shenango Township, Pymatuning Swamp, 2[9]; Linesville (3 mi. NW, 1; 3-1/2 mi. W, 2; 3 mi. W, 1; 2 mi. SW, 1; 7-1/2 mi. SW, 1) 6[9]. Potter County: Cherry Springs Farm, Abbott Township, 1; 3 mi. S Inez, South Fork Sinnamahoning Creek, 1[9]. Sullivan County: Lopez, 1[74]. Lackawanna County: Scranton, 1[1]. Wayne County: Waymart, 1.

Quebec (west to east). Labelle County: Kamika [= Kiamika] Lake, 2[77]; Lacoste, 2[77]; Trout Lake, probably in this county, 2[77]. Megantic County: Black Lake, 1[77].

Rhode Island. Newport County: Middletown, 2[5].

Vermont. Lamoille County: Mt. Mansfield, 1. Windsor County: Barnard, 1[5].

Mustela erminea bangsi Hall

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela erminea bangsi Hall, Journ. Mamm., 26:176, July 19, 1945.

[Putorius] cicognani, Mearns, Bull. Amer. Mus. Nat. Hist., 3:235, June 5, 1891.

Putorius richardsoni cicognani, Bangs, Proc. Biol. Soc. Washington, 10:18, February 25, 1896 (part).

Putorius cicognanii, Cory, Mamm. Illinois and Wisconsin, p. 375, 1912.

Mustela cicognanii, Aldous and Manweiler, Journ. Mamm., 23:250, August 13, 1942.

[125]

Mustela cicognanii cicognanii, Bailey, N. Amer. Fauna, 49:169, January 8, 1927; Leraas, Journ. Mamm., 23:344, August 13, 1942.

Type.—Male, subadult, skull and skin; no. 11541, D. R. Dickey Coll.; Elk River, Sherburne County, Minnesota; November 1, 1925; obtained by Bernard Bailey, original no. A 606.

The skull is complete and the teeth all are present and entire. The skin is well made and in a good state of preservation.

Range.—Southern Manitoba, northeastern North Dakota, the whole of Minnesota, Wisconsin and Michigan and northern Iowa. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. richardsonii, in that, in both sexes, least width of color of underparts averages about a third, instead of two-fifths, of greatest width of color of upper parts, and in that skulls of males are a fifth or more lighter, basilar length averaging less than 40; from M. e. cicognanii, in that hind foot more than 40 in males, averaging 32 versus 30 in females, and in larger skull, depth of skull at plane of molars being 11.4 versus 10.0 in males and 9.1 versus 8.6 in females.

Description.—Size.—Male: Twelve adult and subadult males from Aitkin, Minnesota, yield average and extreme measurements as follows: Total length, 316 (291-341); length of tail, 87 (70-101); length of hind foot, 43 (40-44). Two adults from Aitkin each weigh 170 grams.

Four adult and subadult females from Elk River and Fort Snelling, Minnesota, yield average and extreme measurements as follows: Total length, 249 (240-260); length of tail, 61 (55-65); length of hind foot, 32 (30-33).

Color.—As described in Mustela erminea richardsonii except that, least width of color of underparts averaging, in males from Minnesota, 32 (19-51) per cent of greatest width of color of upper parts. Black tip of tail in 12 male topotypes in white winter pelage averaging 52 (45-58) mm. which is 60 (53-66) per cent of length of tail-vertebrae.

Skull.—Male (based on adults from Aitkin): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight of 2 adults from Aitkin, 2.2, 2.3 grams (9 subadults from T. 61 N, R. 26 W, average 1.95 grams); basilar length, 39.7 (38.5-40.7); length of tooth-rows rarely more (usually less) than length of tympanic bulla.

Female (based on adults from Minnesota as listed in table of cranial measurements, which see): See plates 9-11. As described in Mustela erminea richardsonii except that: Weight, of a subadult from T. 61 N, R. 26 W, 0.91 grams; basilar length, 32.8 (31.8-33.6); breadth of rostrum rarely equal to as much as 30 per cent of basilar length.

From richardsonii, topotypes of bangsi differ in that cranial measurements in males are approximately 7 (5-9) per cent less, linear measurements of teeth are 10 (9-11) per cent less and the skull is a fifth lighter. In relation to basilar length the tympanic bullae of bangsi are longer. Skulls of females are individually indistinguishable, those of bangsi averaging approximately 1 per cent less in linear measurements. Comparison with the smaller cicognanii is made in the account of that subspecies.

Remarks.—Before the subspecific name bangsi was proposed, individuals of this subspecies ordinarily were recorded in the literature as Mustela cicognanii. The best single lot of material is in the zoölogical collection of the University of Wisconsin. The late naturalist Albert Lano preserved a large share of the material from Minnesota. The large series from Elk River of that same state was mostly collected by Bernard Bailey although his Aunt, Anna (Bailey) Mills, and her brother the late Vernon Bailey, at an earlier time saved some specimens from Elk River. The name bangsi was proposed in recognition of the superior work done on American weasels by the late Outram Bangs.

From the range of M. e. invicta in the Rocky Mountains, that of bangsi is separated by the Great Plains from a large part of which region the species is unknown. M. e. bangsi differs from invicta in greater degree of sexual dimorphism in size, and in each sex by larger size, narrower light-colored underparts, and deeper braincase as measured at the anterior margin of the basioccipital. In bangsi the braincase is deeper relative to the length of the skull as well as, of course, actually deeper.

Of the two subspecies whose ranges do meet that of bangsi, it more closely resembles richardsonii than cicognanii. From richardsonii, especially from southeastern populations of the same in which the skull is of the same size as in bangsi, the latter differs in longer hind feet. This is an average difference and by one interpretation the animals here referred to bangsi might be lumped with some of the populations from the southeastern part of the range of richardsonii and the whole lot treated as intergrades between richardsonii and cicognanii. Nevertheless, the animals here referred to bangsi are not geographically intermediate between richardsonii and cicognanii and this consideration had much to do with the decision to recognize as a separate subspecies the animals here named bangsi.

Within the range of the subspecies there is some geographic variation; the hind feet of animals from Iowa average slightly shorter than those of animals from Minnesota and Wisconsin but are nowhere nearly so short as in cicognanii at the same latitude in the eastern United States.

It is noteworthy that the few specimens seen from Isle Royal have the long hind feet of bangsi and not the short hind feet of cicognanii which occurs all along the northern mainland.

Because an oft cited record of occurrence even though erroneous, has a way of being repeated in later works, attention is here called to the alleged occurrence of this ermine in northwestern Ohio at New Bremen. Henninger (1921:239) published the original account of the supposed occurrence but as I pointed out in 1937 (p. 304), the specimen concerned proved upon examination to be a female of Mustela frenata noveboracensis. Henninger was misled probably by the short tail; the end of the tail had been lost and healed over before the animal's death. The present study has revealed that M. erminea everywhere east of the Cascade Mountains assumes a white winter coat. Had this been known when Henninger obtained his specimen he probably would not have wrongly identified the animal from New Bremen which was in the brown, winter pelage.

Specimens examined.—Total number, 222, arranged alphabetically by provinces and states and, arranged from north to south, by counties in each state. Unless otherwise indicated, specimens are in the University of Wisconsin Museum of Zoölogy.

Iowa. Dickinson County: W side Lake Okobogie, 1[48]. Winnebago County: Lake Mills, 7[65]. Worth County: Northwood, 1[65]. Clay County: "Dewey's Pasture, near Ruthven," 1[76].

Manitoba. Aweme, 4[47]; Red River Settlement, 1[91].

Michigan. Isle Royal: Tobin Harbor, 1[76]; Bell Isle, 1[76]; Washington Harbor, 3[76]. Ontonagon County: Ontonagon, 2 (1[76], 1[14]); T. 51N, R. 43W, S. 17, Porcupine Mts., 1[76]. Gogebic County: Little Girls Point, 5[76]; Ironwood, 1[76]. Iron County: no locality more definite than county, 1[76]. Luce County: Tahquamenon River Falls, 1[91]. Chippewa County: Sault Ste. Marie, 2[76]. Emmet County: Wilderness State Park, 2[76]. Cheboygan County: Univ. Mich. Biol. Station, 1[76]. Washtenaw County: Ann Arbor, 1[76].

Minnesota. Kittson County: no locality more definite than county, 1[2]. Roseau County: Deer Township, 1[14]; Falun Township, 2[14]. Marshall County?: Moose River, 5[93]; Warren, definitely in Marshall County, 1[93]. Cook County: Grand Marais, 3 (2[76], 1[14]). St. Louis County: 2 mi. E Babbitt, 14[93]; Burntside [= Burnside] Lake, 1[91]. Itasca County: T. 61N, R. 26W, 23. Clay County: Moorhead, 3[9]. Aitkin County: Aitkin, 13 (11[60], 1[7], 1[4]). Otter Tail County: Arthur, 3[60]; Ten Mile Lake, 1[76]; Parkers Prairie, 2[75]. Chisago County: North Branch, 1[60]. Sherburne County: Elk River, 42 (16[91], 5[14], 20[59], 1[74]). Hennepin County: Lake Minnetonka, 1[75]; Minneapolis, 1[91]; Fort Snelling, 5 (4[2], 1[60]).

North Dakota. Pembina County: Walhalla, 1[91]. Nelson County: Stump Lake, 1[91]. Eddy County: Brantford, 2[76].

Wisconsin. Douglas County: T. 44N, R. 13W, 1; Gordon, 1. Bayfield County: Brinks Camp, Washburn, 1[2]; "near Cable," 1. Ashland County: Bear Lake, 2. Iron County: Fisher Lake, 4; Mercer, 5. Vilas County: Mamie Lake, 16[91]; Ox Bow Lake, 1[91]. Oneida County: Tomahawk Lake, 1[60]. Langlade County: T. 34N, R. 11E, 3. Rush County: Ladysmith, 1. Dunn County: Colfax, 2. Door County: Mink River, Ellison Bay, 1[76]. Dodge County: Fox Lake, 1[50]; Beaver Dam, 12[50].

Mustela erminea invicta Hall

Ermine

Plates 2, 3, 4, 9, 10, 11 and 41

Mustela erminea invicta Hall, Journ. Mamm., 26:75, February 27, 1945; Hall, Journ. Mamm., 26:180, July 19, 1945.

Putorius cicognanii, Preble, N. Amer. Fauna, 27:230, October 26, 1908.

Type.—Male, subadult, skull and skin; no. 101122, Mus. Vert. Zoöl.; Benewah, Benewah County, Idaho; October 24, 1926; obtained by William T. Shaw.

The skull has a hole in the right squamosal bone on the floor of the braincase, and lacks the hamular process of the left pterygoid. The postmolar part of the right lower jaw is missing. The teeth all are present and entire. The skin is in white, winter pelage, well made, and in a good state of preservation.

Range.—Central Rocky Mountain region from Jasper Park south over Alberta, southeastern British Columbia, Washington east of the Cascades, and north and central Idaho and northwestern Montana. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. richardsonii, in males, by skull lighter than 1.9 grams, mastoid breadth less than 19.9, depth of skull at anterior margin of basioccipital less than 12.4, in females by corresponding measurement of depth less than 10.1, and weight of skull less than one gram; from M. e. fallenda, in both sexes, by upper lips white (not brown), in males by skull averaging longer (37.0 versus 35.7), in females by breadth of rostrum less, instead of more, than 30 per cent of basilar length; from M. e. streatori, gulosa, and muricus by hind foot more than 36 and basilar length more than 35 in males and by hind foot more than 29.5 and basilar length more than 30.5 in females; further distinguished from streatori by white (not brown) upper lips and from gulosa by black tip of tail more than half length of tail-vertebrae.

Description.—Size.—Male: Ten adults and subadults from central Idaho County yield average and extreme measurements as follows: Total length, 291 (272-328); length of tail, 86 (75-100); length of hind foot, 39.9 (38-44).

Female: Five adults and subadults from the same locality yield average and extreme measurements as follows: Total length, 255 (245-270); length of tail, 71 (68-76); length of hind foot, 32.3 (32-33).

Color.—As described in Mustela erminea richardsonii except that underparts in summer Marguerite Yellow or more whitish; least width of color of underparts averaging, in four females from Idaho and Montana, 38 (33-43) per cent of greatest width of color of upper parts. Black tip of tail in same specimens 38 (31-42) mm. which is 57 (52-65) per cent of length of tail-vertebrae.

Skull.—Male (5 adults from Idaho County): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.5 (1.4-1.7) grams; basilar length, 37.0 (35.8-39.8).

Female (illustrated by adult and 4 subadults in table of cranial measurements, which see): See plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 0.72 (0.7-0.9) grams; basilar length, 32.2 (31.6-32.8).

From fallenda, invicta differs in that the skull of the male has a relatively narrower rostrum and relatively shallower braincase. Females show the same differences but the degree of difference is about as great again as in males. The teeth are almost exactly the same size in the two subspecies. The weight is the same in males but in females invicta is 18 per cent heavier.

From streatori, invicta differs in that males average larger in every measurement taken except that the anteroposterior diameter of the inner moiety of M1 is less; 36 per cent heavier; linear measurements of the skull are about 5 per cent larger and those of the teeth, with the one exception noted, about 6 per cent larger; relative to the basilar length the tympanic bullae are longer and the rostrum is relatively narrower. In females, measurements of the skull average 8 per cent more and those of the teeth 7 per cent more except that, as in males, the inner lobe of M1 is actually shorter. Females of invicta are 12 per cent heavier; relative to the basilar length the skull is narrower throughout and the tooth-rows are shorter than in streatori.

From gulosa, invicta differs in that males average larger (about 12 per cent) in every measurement taken, excepting the anteroposterior diameter of M1 which is the same; 50 per cent heavier; relative to the basilar length the length of the tooth-rows and interorbital breadth are less. In females the inner lobe of M1 is smaller but every other measurement taken of the skull and teeth is more, invicta averaging about 8 per cent larger and 22 per cent heavier; relative to the basilar length, the tooth-rows are shorter and the skull is narrower interorbitally, through the rostrum and across the zygomata.

From murica, invicta of corresponding sex differs in being larger in every measurement taken; males average 17 per cent larger in cranial measurements, 13 per cent larger in dental measurements and are 83 per cent heavier; corresponding percentages for females are 11, 9 and 20. Exception must again be made for the anteroposterior diameter of the inner lobe of the last upper molar which is less in females, and only slightly more in males. In males of invicta the tympanic bullae are longer in relation to the basilar length.

From the geographically remote cicognanii, skulls of both males and females of invicta are to me individually indistinguishable. There is, nevertheless, an average difference not apparent to the eye between skulls of males. If the length of the tooth-rows be taken as a standard (100 per cent), the rostrum, of invicta, as measured across the lacrimal processes is broader (89 rather than 84 per cent) but the width across the fourth upper premolars is less, 94 rather than 97 per cent of the length of the tooth-rows.

Since the skull of invicta closely resembles that of cicognanii, it follows that invicta differs from richardsonii and bangsi in about the manner described in the account of cicognanii.

Remarks.—Animals of this subspecies in advance of the present study generally were recorded in the literature under the name Mustela cicognanii. The difficulty in distinguishing individual specimens of invicta on morphological grounds from those of the geographically remote M. e. cicognanii should not be taken to indicate that the populations do not differ appreciably. Actually they differ in several characters although in no one of these is the degree of difference sufficient to allow of using it alone as a certain means of diagnosis. In invicta, as compared with cicognanii, the light-colored underparts are wider in relation to the dark-colored upper parts and the tail is longer by 4 per cent relative to the head and body. Given a population of each of the two subspecies, in which the skull is of the same mass, the hind feet are longer in invicta, there is more sexual dimorphism in size, and the anterior part of the skull differs in some particulars as just described in the comparison of the skull of invicta with other forms. Nevertheless, each of these differences is of an average sort. Therefore, and because overall size is about the same in the two subspecies concerned, one or a few specimens from, say, central Idaho, can be distinguished from animals from western Pennsylvania only with difficulty, if at all. The close resemblance of skulls of invicta and cicognanii may be a function of their living at approximately the same latitudinal position in a climate that has marked seasonal variation.

Intergradation with richardsonii is complete and gradual; in one sense invicta is but little more than a small richardsonii. Intergradation with fallenda is shown by several specimens. These two races differ in large degree in color, and in size and shape of the skull of females. Although the geographic area where intergradation in color occurs is fairly wide, the area in which intergradation in cranial characters in females occurs, appears, from the inadequate material available, to be much narrower. Intergradation occurs freely in Washington with streatori but with muricus so far as known only in the Bitterroot and nearby mountains of northwestern Montana. The Snake River Plains and low country along much of the Columbia River appears to be uninhabited by weasels of the species erminea and hence there is opportunity for intergradation only in the mentioned area of Montana.

Specimens examined.—Total number, 177, as follows. Arranged alphabetically by provinces and states then by localities from north to south in each province and by counties from north to south in each state. Unless otherwise indicated, specimens are in the United States National Museum.

Alberta. Jasper House, 4[77]; Shovel Pass, 2[77]; Jasper Park, 10[77]; head of Smoky River, 9; Henry House, 2 (1[77]); Blindman River, 1[2]; forks of Blindman River and Red Deer River, 2 (1[60], 1[75]); "near Red Deer, Red Deer River," 1[77]; Red Deer River, 2 (1[2], 1[60]); Red Deer, 2[60]; Rosebud, 2[77]; Prairie, 3000 ft., 1; Didsbury, Little Red Deer River, 1; Canadian Nat'l Park, 1[60]; Canmore, 1; Banff, 1[60]; High River, 1[86]; "Waterton Lake Park" in Alberta, 6[77].

British Columbia. Grand Forks of Fraser River, 1; Canoe River, 1[77]; Field, 1; Glacier, 1[58]; E side Beaverfoot Range, 4000-4500 ft., 6 mi. SE Fraser Creek, 8[74]; Wentworth Lake, 1[31]; Revelstoke, 2 (1[77], 1[60]); Spillimacheen[e]en River, 2[2]; Sicamous, 2; Albert River, 7000 ft., 1[2]; Lumby, Creighton Valley, 1[31]; Okanagan, 4 (2[75], 1[94], 1[2]); Kettle River Lake, Gold Range, 4000 ft., 1; Crows Nest Station, 1[74]; Yale District, 3; Fort Hope, 1; Chilliwack Lake, 1[77]; Skagit, 2 (1[77], 1[31]); Skagit Valley, 1[77]; Skagit Summit, 1[77]; Lightning Lakes, 2 mi. N International Boundary, 3; Osoyoos-Bridesville Summit, 2; Westbridge, 1[77]; Rossland, 5[77]; Creston, mouth Goat Creek, 3[77]; Yahk, 4[77].

Idaho. Bonner County: Coolin, 4. Benewah County: Benewah, 1[55]. Idaho County: "Pete Kings, Lochsa River," 1[97]; 2 mi. SSE Selway Falls, 1900 ft., 1[8]; 4 mi. SW Selway Falls, 5800 ft., 3[8]; Newsome Cr., 12 mi. above jct. with S Fk. Clearwater River, 2[74]; Iron Mt., to 14 mi. W thereof, 24[74]; Pilot Cr., 3/4 to 2-1/2 mi. above Newsome Cr., 4[74]; Sawmill Cr., 1-1/4 mi. W Newsome, 1[74]; between Selway River and S. Fk. Clearwater R., 4[74].

Montana. Teton County (of old arrangement of counties): Many Glacier, 4900 ft., 1[74]; Duck Lake, 6 mi. NE St. Marys Lake, 1; St. Marys, Glacier Park, 1[76]; Lower St. Marys Lake, 1[2]. Flathead County: Stanton Lake, 5. County in question: Bitter Root Mts., 1. Ravalli County: Tin Cup District, 1[74]; Bass Creek, 6800 ft., NW of Stevensville, 1; Capitan Peak, 7000 ft., 1; Darby, 2[74]; Girds Creek, 1[74]; Charlos Heights, 2[74].

Washington. Whatcom County: Twin Lakes, Winchester Mts., 3 (1[10]); Chilliwack River, 2600 ft., 2; Cooper Creek, near head, 4500 ft., Hannegan Pass, 1; Cooper Cr., 4300 ft., Hannegan Pass, 1[10]; Beaver Creek (2500 ft., and at McMillan Ranch, 1700 ft.), 2; Barron, Bornite Mine, 5000 ft., 1. Okanogan County: Tungsten Mine, 6800 ft., Bauerman Ridge, 4; Hidden Lakes, 4100 ft., 1; West Fork Pasayten River, 4700 ft., 1. Stevens County: Orin, 1[51]. Pend Oreille County: Ione, 2[51]. Chelan County: Lake Chelan, 1[46].

Mustela erminea alascensis (Merriam)

Ermine

Plates 2, 3, 4, 9, 10 and 11

Putorius richardsoni alascensis Merriam, N. Amer. Fauna, 11:12, pl. 2, figs. 2, 2a, June 30, 1896.

Putorius cicognanii alascensis, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Swarth, Univ. California Publ. Zoöl., 7:140, January 12, 1911.

Mustela erminea alascensis, Hall, Proc. Biol. Soc. Washington, 57:36, June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.—Male, adult, skull and skin; no. 74423, U. S. Nat. Mus., Biol. Surv. Coll.; Juneau, Alaska; August 22, 1895; obtained by Clark P. Streator, original no. 4806.

The skull shows malformation of the frontal sinuses due to parasites and lacks osseous tissue where the parasitic infestation was localized. The left exoccipital condyle and adjacent region is less developed than the right and the posterior part of the skull is bent slightly to the left. Otherwise the skull is unbroken. The teeth all are present and entire. The skin is in the brown summer coat, fairly well made and in a good state of preservation. A few white hairs persist where the proximal line of the black hair of the tip of the tail meets the distal line of the brown hair.

Range.—Mainland of southeastern Alaska from Lynn Canal south to include Mitkof, Zarembo, Wrangel and Revillagigedo islands. See figures 25, 26 on pages 95 and 134.

Characters for ready recognition.—Differs from M. e. arctica and haidarum, in both sexes, by proximal two-thirds of under side of tail colored same as upper parts rather than same as underparts and interorbital breadth less, instead of more, than distance between glenoid fossa and posterior border of external auditory meatus; from M. e. salva, in males, by overall depth of braincase including tympanic bullae less than 89 per cent of orbitonasal length, females not individually distinguishable but averaging shallower through the braincase; from M. e. initis, celenda and seclusa by interorbital breadth less than distance between glenoid fossa and posterior border of external auditory meatus (females of initis, celenda and seclusa unknown); further from initis by total length less than 317 and black tip of tail less than 57 per cent of length of tail-vertebrae; further from celenda by chest white, not mostly covered by brown patch.

Description.—Size.—Male: Eight adults from Windham, Alaska, yield average and extreme measurements as follows: Total length, 298 (288-315); length of tail, 88 (84-94); length of hind foot, 41.3 (37-44).

Female: Two adults from Juneau and Helm Bay measure, respectively, as follows: Total length, 258, 258; length of tail,——, 76; length of hind foot, 32, 34.

Color.—As described in Mustela erminea richardsonii except that least width of color of underparts averaging, in five females, 42 (35-53) per cent of greatest width of color of upper parts. Black tip of tail in same specimens averaging 36 (30-40) mm. which is 49 (48-53) per cent of length of tail-vertebrae.

Skull.—Male (based on 8 adults from Windham): See measurements and plates, 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.8 (1.5-2.6) grams; basilar length, 37.5 (36.5-38.9); length of tooth-rows more or less than (about same as) length of tympanic bulla.

Female (based on 5 adults, from localities listed in the table of cranial measurements): See measurements and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 0.96 (0.7-1.1) grams; basilar length, 32.7 (31.9-33.2); breadth of rostrum more or less than (about equal to) 30 per cent of basilar length.

From richardsonii, alascensis differs in that the skull of the male averages smaller in every measurement taken and is 28 per cent lighter. Relative to the basilar length, the orbitonasal length is more and the braincase is shallower as measured at the anterior end of the basioccipital. The four adult females seen of alascensis are more variable than those of richardsonii and average smaller in some measurements and larger in others but give no proof of any consistent difference.

From haidarum, alascensis differs in that the rostrum and entire preorbital part of the skull is actually as well as relatively much smaller in both sexes. In males of alascensis the length of the skull, and other cranial measurements of length, is more. In males, the mastoid breadth and zygomatic breadth are about the same as in haidarum, as also is the weight. M1 is larger but m1 and P4 are smaller. In females the anteroposterior extent of the inner moiety of M1 and length of tympanic bulla are about the same in the two subspecies but all other cranial and dental measurements in alascensis are less. It is 29 per cent lighter. The difference in the preorbital region is of about the same degree as in the males.

Comparisons of the skull with those of arctica, salva, initis, celenda, and seclusa are made in the accounts of those subspecies.

Remarks.—The relatively few specimens known of this race seem always to have been referred to in the literature by the name alascensis and the nomenclatural history is therefore simple. The original materials were obtained by the collector Clark P. Streator and the additional series of skeletons, one with skin, from Windham were procured by Stanton Price, a resident there.

The subspecies is well differentiated from both arctica and richardsonii. Although actual intergrades are lacking between alascensis and the two races just mentioned I have no doubt that intergradation occurs with richardsonii and think it probably does also with arctica.

The assignment of the three females from Mitkof Island, Zarembo Island, and Loring on Revillagigedo Island, is tentative because each is so young as not to show diagnostic cranial characters. The two other specimens from Revillagigedo Island (Carroll Inlet), labeled as males, are in white winter pelage. Only one, no. 136358, a subadult, is accompanied by a skull. The small size of each specimen, and its cranial characters which are intermediate between those of males and females of alascensis of the adjacent mainland, indicate the existence of a distinct race of weasel on Revillagigedo Island. On the chance that the one specimen with a skull is a dwarf, or is wrongly sexed as seems improbable, the population is tentatively referred to alascensis.

Fig. 26. Map showing known occurrences and probable geographic ranges of the subspecies of Mustela erminea in southeastern Alaska.

Specimens examined.—Total number, 24, arranged by localities from north to south. Unless otherwise indicated, specimens are in the Museum of Vertebrate Zoölogy, University of California.

Alaska. Juneau, 5[91]; Taku River, 1; Windham, 9; Mitkof Island, 1; St. John Harbor, Zarembo Island, 1; Wrangel, 1[91]; Helm Bay, Cleveland Peninsula, 1; Cleveland Peninsula, 2[91]; Revillagigedo Island, Carroll Inlet, 2[91]; Loring, 1[91].

Mustela erminea salva Hall

Ermine

Plates 2, 3, 4, 9, 10 and 11

Mustela erminea salva Hall, Proc. Biol. Soc. Washington, 57:35, June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.—Male, adult, skull only; no. 74641, Mus. Vert. Zoöl.; Mole Harbor, Admiralty Island, Alaska, December 27, 1936; obtained by A. Hasselborg.

The skull (plates 2-4) shows malformation of the frontal sinuses owing to parasites and lacks osseous tissue where the parasitic infestation was localized. The skull is unbroken. The teeth all are present and entire.

Range.—Admiralty Island, Alaska. See figures 25, 26 on pages 95, 134.

Characters for ready recognition (known only from skulls).—Differs from males of M. e. alascensis in overall depth of braincase which is more than 89 per cent of orbitonasal length; from M. e. initis, in males, in that orbitonasal length and mastoid breadth total less than 35 mm., weight of skull and lower jaws less than 2.1 grams; from M. e. celenda, in males, in that breadth of rostrum measured across lacrimal processes less than a third of basilar length.

Description.—Size.—Male: An adult from Gambier Bay measures: Total length, 320; length of tail, 95; length of hind foot, 45 (41 in dry skin).

Female: A subadult from Hawk Inlet, measures: Total length, 250; length of tail, 70; length of hind foot, 33.

Color.—As described in Mustela erminea richardsonii except that least width of color of underparts in four individuals 40 (38-43) per cent of greatest width of color of upper parts. Black tip of tail, in two individuals for which external measurements are given, amounting to 50 and 40 mm. respectively which is 53 and 57 per cent of length of tail-vertebrae.

Skull.—Male (type and 4 adult topotypes): See measurements and plates 2-4. As described in Mustela erminea richardsonii except that: Weight, 1.7 (1.5-1.9) grams; basilar length, 37.8 (36.4-39.5, extremes are in subadults); length of tooth-rows more or less (usually more) than length of tympanic bulla; interorbital breadth rarely more than distance between glenoid fossa and posterior border of external auditory meatus.

Female (2 ad. and 1 ad.-sad. topotypes): See measurements, and plates 9-11. As described in Mustela erminea richardsonii except that: Weight, 0.9 (0.8-1.0) grams; basilar length, 33.0 (32.0-33.6); length of tooth rows approximately same as length of tympanic bulla; breadth of rostrum approximately 30 per cent of basilar length.

From alascensis, salva differs in that males have the preorbital region slightly wider in relation to the length of the tympanic bulla; also the braincase is smaller, actually as well as in comparison with the preorbital part of the skull. The tympanic bullae do not project so far below the squamosals and the braincase itself is shallower, in adults averaging only 11.5 mm. as against 12.5 mm. The overall depth of the braincase, including the tympanic bullae, when divided into the orbitonasal length gives an average of 93 (90-97) per cent whereas in alascensis the figure is only 85 (78-88) per cent. On this basis alone, everyone of the adult skulls of the two races can be distinguished. The females and subadult males show the same tendency to reduction in depth of braincase but not every individual among them can be surely distinguished. By weight the skull of salva of corresponding sex is only about 6 per cent smaller. Comparisons with initis and celenda are made in the accounts of those subspecies.

Remarks.—Most of the specimens seen were collected by Allen E. Hasselborg, resident on Admiralty Island. On the basis of skulls—few skins, and measurements taken in the flesh, are available—salva more closely resembles alascensis than does any other subspecies so far known from southeastern Alaska. The race on Admiralty Island is only slightly differentiated from alascensis of the adjacent mainland.

Specimens examined.—Total number, 26, all from Admiralty Island, Alaska, arranged in general by localities from north to south, and unless otherwise indicated in the Museum of Vertebrate Zoölogy, University of California.

Alaska. Admiralty Island: Hawk Inlet, 2; Seymour Canal, 4; Mole Harbor, 18 (skulls only); Gambier Bay, 1; no locality more definite than Admiralty Island, 4 (1 in U. S. Nat. Mus.).

Mustela erminea initis Hall

Ermine

Plates 4, 5 and 6

Mustela erminea initis Hall, Proc. Biol. Soc. Washington, 57:37, June 28, 1944; Hall, Journ. Mamm., 26:180, July 19, 1945.

Type.—Male, adult, skull and skin; no. 289, Mus. Vert. Zoöl.; Saook Bay, Baranof Island, Alaska; October 9, 1907; obtained by A. Hasselborg, original no. 4.

The top of the skull is fractured on the left side from the anterior nares posteriorly through the postorbital process to the posterior root of the zygomatic arch. On the left lower jaw the canine and three incisors are missing; otherwise the teeth all are present and entire.

The skin is in process of molt, approximately nine-tenths of the incoming white pelage being in place. The skin is well made and in a good state of preservation.

Range.—Chichagof and Baranof islands, Alaska. See figures 25, 26 on pages 95, 134.

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Characters for ready recognition (only males known).—Differs from M. e. arctica, in that proximal two-thirds of under side of tail colored same as upper parts rather than same as underparts, zygomatic breadth less than distance between last upper molar and jugular foramen; from M. e. salva in that orbitonasal length and mastoid breadth total more than 35 mm., weight of skull and lower jaws more than 2.1 grams; from M. e. alascensis, by total length more than 317, black tip of tail more than 57 per cent of length of tail-vertebrae, interorbital breadth more than 10.3 and equal to, instead of less than, distance between glenoid fossa and posterior border of external auditory meatus; from M. e. celenda by chest white (not mostly covered by brown patch), breadth of rostrum measured across lacrimal processes less than a third of basilar length; from M. e. seclusa in zygomatic breadth more than distance between last upper molar and jugular foramen.

Description.—Size.—Male: The type and an adult topotype measure, respectively, as follows: Total length, 330, 320; length of tail, 95, 95; length of hind foot, 45, 45.

Female: No external measurements available.

Color.—As described in Mustela erminea richardsonii except that least width of color of underparts averages, in two young female topotypes, 50 (49, 50) per cent of greatest width of color of upper parts. Black tip of tail in three young female topotypes averaging 54 (52-55) mm. which is 67 (63-69) per cent of length of tail-vertebrae.

Skull.—Male (illustrated by type and 1 ad. topotype): See measurements and plates 4-6. As described in Mustela erminea richardsonii except that: Weight, 2.3 and 2.5 grams; basilar length, 39.6, and 40.5; interorbital breadth equal to distance between glenoid fossa and posterior border of external auditory meatus.

Female: No adults available.

From salva, initis differs in that skulls of males average larger in every measurement taken, being 41 per cent heavier. Relative to the basilar length, the interorbital and preorbital parts of the skull are larger; the relatively greater interorbital and mastoid breadths are particularly noticeable. Although the depth of the braincase, including the tympanic bullae, is both relatively as well as actually more than in salva, the depth is relatively less than in alascensis which otherwise differs from initis in about the same way that salva differs from initis. Whereas the interorbital breadth in initis is about equal to the distance between the glenoid fossa and the posterior border of the external auditory meatus, the interorbital breadth is uniformly less than this distance in both salva and alascensis. In comparison with seclusa the teeth are of the same size but all measurements of the skull are larger. The skull of initis is 25 per cent heavier. In relation to the basilar length, the interorbital and preorbital parts of the skull are much less in initis. The preorbital and interorbital regions in initis are relatively smaller in comparison also with arctica. The one measurement of interorbital breadth in initis is greater in relation to the basilar length than in kadiacensis but the rostral region, and all that part of the skull anterior to the braincase, is relatively smaller in initis.

Remarks.—The two adult males, nos. 286 and 289 from Saook Bay, provide convincing evidence of the existence of a distinct race of weasel on Baranof Island. Three other young specimens, almost subadult, from the same place are labeled as males although the basilar lengths of these skulls are only 35.5, 35.9 and 37.3 millimeters as against 39.6 and 40.5 in the two adult males. The difference in size is too great to be age-variation. The fact that 3 are definitely of one category and 2 of the other makes it doubtful that individual variation accounts for the differences. The small size of these 3 specimens and the fact that in each the anterior margin of the tympanic bulla is flush with the squamosal rather than protruded from the braincase, suggests that the three are females. If they are females, the amount of secondary sexual variation is rather less than would be expected by analogy with the amount obtaining in alascensis on the mainland and in salva on Admiralty Island. Another possibility that I can not disprove is that two stocks of weasels persist on Baranof Island, the two larger specimens being descendants of the stock which first became established on the island and the three smaller specimens being descendants of an individual ermine, or of ermines, that were rafted or otherwise transported to the island at a considerably later date. Assuming for the moment that there are two stocks, it must be admitted that each one differs from any stock known from elsewhere. Therefore, each stock would be presumed to have been long resident on the island. But—two stocks as closely related as the two in question would not be expected to persist for long in an area as small as that of Baranof Island because competition would give one the ascendancy. Therefore, the first suggestion, namely that the three smaller animals are really females, seems the more probable. The feasible way to clear up the present uncertainty is, of course, to obtain additional specimens, carefully labeled as to sex. Yet another reason why additional collecting is desirable in this area is to ascertain whether there is subspecific differentiation between the ermines of Baranof and Chichagof islands. The one specimen available from the latter island, although in general like the three smaller animals from Baranof Island, differs in the fuller (less scooped out) medial side of the tympanic bulla and to a slight degree in each of some other features. This specimen from Chichagof Island is labeled as a male also.

Specimens examined.—Total number, 6, arranged by localities from north to south, and in the Museum of Vertebrate Zoölogy, University of California.

Alaska. Chichagof Island, Freshwater Bay, 1. Baranof Island, Saook Bay, 5.

Mustela erminea celenda Hall

Ermine

Plates 5, 6 and 7

Mustela erminea celenda Hall, Proc. Biol. Soc. Washington, 57:38, June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

Type.—Male, adult, skull and skin; no. 130987, U. S. Nat. Mus., Biol. Surv. Coll.; Kasaan Bay, Prince of Wales Island, Alaska; June 16, 1903; obtained by Cyrus Catt; original no. 4407X.

The skull has a piece 1.5 mm. long broken out of the left zygomatic arch. P2 is absent on both sides. The right I1, and the left I1 and I2 are missing. The skin, in summer pelage, is fairly well made. A scrotal pouch attests to the correctness of the sex recorded on the label. The rostral part of the skull is smaller than in average-sized males of corresponding age.

Range.—Prince of Wales, Dall, and Long islands, Alaska. See figures 25, 26 on pages 95, 134.

Characters for ready recognition (only males known).—Differs from M. e. alascensis and initis in chest mostly covered by brown patch, not white, and breadth of rostrum measured across lacrimal processes more than a third of basilar length, which cranial character serves to distinguish also salva; from M. e. seclusa in zygomatic breadth less than distance between last upper molar and jugular foramen; from M. e. haidarum in chest white (not mostly covered by brown patch), proximal two-thirds of underside of tail colored like upper parts rather than underparts, basilar length more than 38.2 mm.

Description.—Size.—Male: Seven adults and subadults from Prince of Wales Island, yield average and extreme measurements as follows: Total length, 286 (277-304); length of tail, 77 (74-85); length of hind foot, 36 (35.5-40.5).

Female: No specimen available.

Color.—As described in Mustela erminea richardsonii except that upper parts about tone 3 of dark Chocolate Brown of Oberthür and Dauthenay, pl. 342; lower throat and chest covered by a large patch of same color as upper parts; color of underparts extending to toes but in interrupted fashion on both fore- and hind-feet; least width of color of underparts averaging, in four males from Prince of Wales Island, 41 (38-49) per cent of greatest width of color of upper parts. Black tip of tail averaging, in 8 males in winter pelage, 65 (59-78) mm. which is 84 (69-92) per cent of length of tail-vertebrae.

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From its geographic neighbors alascensis and initis, celenda differs in darker color of upper parts, presence rather than absence of patch of dark color on lower throat and chest, and longer black tip on tail. From haidarum, celenda differs in darker color of upper parts, presence rather than absence of patch of dark color on lower throat and chest, narrower light-colored under parts, black tip of tail averaging less rather than more than nine-tenths of length of tail-vertebrae and ventral face of tail colored like upper parts rather than like underparts.

Skull.—Male (illustrated by 5 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 2.3 (2.2-2.5) grams; basilar length, 39.5 (38.9-40.7) mm.; length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth more or less than (about equal to) distance between last upper molar and jugular foramen.

Female.—Complete skull of adult unavailable.

Differences from richardsonii are indicated in the formal description just given. Additional to differences therein noted, celenda differs from initis in larger interorbital and preorbital parts of the skull although dimensions of other parts of the skull and the teeth are about the same or even less. From salva, celenda differs in larger average size in every measurement taken, except for the inner moiety of M1 which is about the same. The skull of celenda is 35 per cent heavier. In relation to the basilar length the skull of celenda is wider, especially in the interorbital and preorbital regions. In comparison with alascensis the tympanic bullae are of approximately the same length; otherwise essentially the same differences obtain as are noted in comparison with salva and the zygomatic breadth is relatively more in celenda. From seclusa, in which the teeth are of comparable size, celenda differs in that every cranial measurement is more and the skull is 28 per cent heavier. Because the skull of celenda is so much longer, its dimensions in other planes are less in relation to the length than in seclusa. M. e. celenda is larger in every part measured than haidarum, 21 per cent heavier, and in relation to the basilar length the interorbital, and preorbital, parts of the skull are smaller, the braincase is shallower, and the skull is relatively wider across the zygomata and mastoid processes. In comparison with kadiacensis, differences are: 26 per cent lighter, skull shorter; in relation to the basilar length, braincase shallower as measured at the anterior end of the basioccipital, tooth-rows shorter but orbitonasal length more. In comparison with arctica all parts measured of the teeth and skull of celenda are smaller and its skull is 34 per cent lighter. In relation to the basilar length, the interorbital breadth of celenda is only slightly less but its skull is narrower across the rostrum and zygomata, the tooth-rows are shorter, and the braincase is shallower.

Remarks.—The late George Willett in the course of his work in Alaska collected most of the known specimens of this strongly differentiated subspecies. In both coloration and cranial characters the distinguishing features are so well marked that the zoölogist could with reason accord full specific rank to celenda. Nevertheless it obviously is an ermine. Also, races from other islands of southeastern Alaska tend to bridge the gap, as regards cranial features, between celenda and the mainland ermine. The specimen from Dall Island agrees in all respects with topotypes. The specimen from Howkan on Long Island is in white winter pelage and the skull has suffered shrinkage from some chemical solution; the reference of this specimen to celenda is tentative.

Specimens examined.—Total number, 25, as follows: Arranged by localities from north to south. Unless otherwise indicated, in U. S. National Museum.

Alaska. Prince of Wales Island: Craig, 18 (10 in Mus. Vert. Zoöl., and 8 in Los Angeles Mus. Hist. Art and Sci.); Kasaan Bay, 2; no locality more definite than the Island itself, 3; Dall Island, Otter Harbor, 1 (Los Angeles Mus. Hist. Art and Sci.). Long Island, Howkan, 1 (Field Mus. Nat. Hist.).

Mustela erminea seclusa Hall

Ermine

Plates 5, 6 and 7

Mustela erminea seclusa Hall, Proc. Biol. Soc. Washington, 57:39, June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

Type.—Male, adult, skull alone; no. 31232, Mus. Vert. Zoöl.; Port Santa Cruz, Suemez Island, Alaska; March 24, 1920; obtained by George Willett.

The skull (plates 5-7) is complete and unbroken. Of the upper incisors only right I3 is present. Otherwise the teeth are present and unbroken.

Range.—Known only from the type locality. See figures 25, 26 on pages 95, 134.

Characters for ready recognition (only the male known).—Differs from M. e. celenda in basilar length less than 38.2, from M. e. salva, initis and haidarum in zygomatic breadth more than distance between last upper molar and jugular foramen.

Description.—Size and Color.—No external measurements or skins available.

Skull.—Male: See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.8 grams; basilar length, 34.3; length of tooth-rows about the same as length of tympanic bulla; breadth of rostrum measured across lacrimal processes more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior margin of external auditory meatus; zygomatic breadth more than distance between last upper molar and jugular foramen.

Female.—Skull not available.

From alascensis and salva, seclusa differs in larger teeth, shorter skull, much larger preorbital and interorbital regions, actually as well as in relation to basilar length. Excepting the teeth, which are of about the same size, the same general differences obtain in comparison with initis which, however, is 29 per cent heavier.

From celenda, seclusa differs in smaller skull in all parts measured, being 22 per cent lighter. The teeth are about the same size. In relation to its length the skull of seclusa is much broader and deeper. From haidarum, seclusa differs in: teeth larger; skull shorter and more convex in dorsal outline along median longitudinal axis; in relation to basilar length, skull broader, deeper and braincase relatively shorter.

Remarks.—The characters shown in the one available skull are far outside the limits of individual variation for other known subspecies. Other specimens are much to be desired to ascertain what the "average" individual is like and to learn the characters of the female.

Specimen examined.—One, the holotype.

Mustela erminea haidarum (Preble)

Ermine

Plates 5, 6, 7, 11, 12 and 13

Putorius haidarum Preble, Proc. Biol. Soc. Washington, 12:169, August 10, 1898.

Mustela haidarum, Miller, U. S. Nat. Mus. Bull., 79:97, December 31, 1912.

Mustela erminea haidarum, Hall, Proc. Biol. Soc. Washington, 57:38, June 28, 1944; Hall, Journ. Mamm., 26:181, July 19, 1945.

Type.—Male, adult, skull, skeleton and skin; no. 94430, U. S. Nat. Mus., Biol. Surv. Coll.; Massett, Queen Charlotte Islands, British Columbia; March 17, 1898; obtained by J. H. Keen; original no. 1800x.

The skull is unbroken and complete except for osseous tissue destroyed in the region of each postorbital process; this is the result of infestation of the frontal sinuses by parasites. The skeleton is complete down to the distal ends of the tibiae; the more distal bones are in the skin. The first, right, upper incisor is missing. Otherwise the teeth all are present and entire.

The skin is in the white, winter pelage but the new under fur is visible along the back and on the head although mostly covered with white hair.

Range.—Queen Charlotte Islands. See figure 25, page 95.

[143]

Characters for ready recognition.—Differs from M. e. celenda in chest white (not mostly covered by brown patch), proximal two-thirds of under side of tail colored like underparts instead of upper parts, in males basilar length less than 38.2; from M. e. seclusa, in male, in zygomatic breadth less than distance between last upper molar and jugular foramen; from M. e. richardsonii and alascensis, in both sexes, in proximal two-thirds of under side of tail colored like underparts instead of upper parts, interorbital breadth not less than distance from glenoid fossa to posterior margin of external auditory meatus; from M. e. anguinae and fallenda, in both sexes, in light-colored underparts more than half the width of dark-colored upper parts, proximal two-thirds of under surface of tail colored like underparts instead of upper parts, interorbital breadth equal to or more than distance between glenoid fossa and posterior margin of external auditory meatus.

Description.—Size.—Male: Two adults, U.S.N.M., no. 100622, from Cumsheva Inlet, and Amer. Mus. N. H., no. 37411, and the type, measure, respectively, as follows: Total length, 283, 290, 275; length of tail, 70, 75, 60; length of hind foot, 39, 40, 37.

Female: Corresponding measurements of an adult, no. 100624, and a young individual, no. 100623, each from Cumsheva Inlet, are: 252, 250; 63, 61; 31, 32.

Color.—As described in Mustela erminea richardsonii except that underparts not Sulphur Yellow but ranging from near (e) Colonial Buff through Marguerite Yellow to almost pure white; color of underparts extends distally on posterior sides of forelegs and onto toes but in many specimens interrupted at wrist by color of upper parts; color of underparts extends onto proximal three-fourths of under side of tail as length of tail is measured along tail-vertebrae; least width of color of underparts averaging, in 5 males, 79 (66-130) per cent of greatest width of color of upper parts. Black tip of tail in same males averaging 62 (60-70) mm. which is 92 (83-115) per cent of length of tail-vertebrae.

The close correspondence in color-pattern of this weasel with the Arctic races, arctica, polaris, semplei and kadiacensis is noteworthy, and distinguishes it from weasels on the adjacent mainland and adjoining islands to the north and south. The color of the upper parts is darker than in the four Arctic races named.

Skull.—Male (7 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.9 (1.7-2.0) grams; basilar length, 36.7 (35.6-37.5); length of tooth-rows more than length of tympanic bullae; breadth of rostrum measured across lacrimal processes more than a third of basilar length; interorbital breadth more than distance between glenoid fossa and posterior margin of external auditory meatus; zygomatic breadth barely less than distance between last upper molar and jugular foramen.

Female (2 adults): See measurements and plates 11-13. As described in Mustela erminea richardsonii except that: Weight, 1.3 and 1.4 grams; basilar length, 34.2; length of tooth-rows more or less than (about equal to) length of tympanic bulla; breadth of rostrum more than 30 per cent of basilar length; interorbital breadth not less than distance between glenoid fossa and posterior margin of external auditory meatus.

From richardsonii, haidarum differs in that skull of the male is actually larger in its anterior part (breadth of rostrum, interorbital breadth and orbitonasal length) but all measurements of other parts average less. In relation to the basilar length, the tympanic bulla is shorter but all other measurements are more. In the skull of the female, which is 23 per cent heavier, the width of the tympanic bulla and anteroposterior extent of the inner lobe of M1 are the same; in all other measurements the female of haidarum is larger, and in relation to the basilar length all measurements are more except the depth of the skull at the anterior margin of the basioccipital and the width of the tympanic bulla, which are less. By actual weight the skull of the male is 25 per cent lighter and the skull of the female 24 per cent heavier than in richardsonii. From fallenda and anguinae, haidarum differs in that measurements of the skulls of both sexes either average more, or are uniformly more, with two exceptions. These are the lesser length and breadth of the tympanic bulla, in comparison with males of fallenda, and the dimensions of M1 which are about the same in all three races concerned. The pre- and interorbital parts are larger in relation to the remainder of the skull. The postorbital breadth is actually a third more than in fallenda. In relation to the basilar length, the tympanic bulla is shorter and the braincase deeper than in males of anguinae. The skull of the male is 27 per cent heavier than that of fallenda and 58 per cent heavier than that of anguinae. The skull of the female is 59 and 50 per cent heavier than those of fallenda and anguinae, respectively. Comparison of the skull with those of alascensis, celenda and seclusa has been made in the accounts of those subspecies.

Remarks.—The available specimens of this ermine were obtained by J. H. Keen in 1898, Wilfred H. Osgood and E. A. Lewis in 1900, W. W. Brown in 1914, J. A. Munro in 1917 and 1918, and Allan Brooks in 1920. M. e. haidarum has more claim to full specific status than any other race of ermine because the diagnostic structural features are numerous and individually of relatively great degree. Indeed, individual variation appears not to bridge the gap between any population of haidarum and other subspecies and strong reasons could be advanced for according haidarum the status of a full species. It differs from the subspecies of erminea on the adjoining mainland and adjoining islands to the north and south and agrees with the Arctic races (arctica, polaris, semplei and kadiacensis) in great extent of the color of the underparts, extension of this color onto the underneath side of the tail, long black tip of the tail and general form of the skull including the relatively heavy preorbital region. The color although darker than in the Arctic subspecies, is lighter than in the insular races immediately to the north and south. In combination, the features mentioned could be taken as indication that haidarum is a relict population from a former glacial period. Assuming that it is a relict population, the color may have become slightly darker since that period but the main response appears to have been a decrease in size for this is a much smaller animal than the Arctic ermines. The size is about what would be expected if one were to judge by the slightly larger ermines on the islands of southeastern Alaska to the north and the smaller ermine on Vancouver Island to the south.

The ermines of the islands of southeastern Alaska, excepting possibly the incompletely known seclusa, have fewer characters of the Arctic races and more characters of the races of the adjoining mainland. Therefore, a possible inference is that the distinctive characters of ermines of the Alaskan islands developed with the aid of isolation from stocks which reached the islands after the glacial period. M. e. haidarum may have found its way to the Queen Charlotte Islands in the glacial period.

Specimens examined.—Total number, 17, as follows. Arranged by locality from north to south. Unless otherwise indicated, specimens are in the U. S. National Museum.

British Columbia. Queen Charlotte Islands. Masset, 7 (4[74], 1[2], 1[59]); Skidegate, 1; Graham Island, 5 (2[94], 1[77], 1[2]); Cumsheva Inlet, 3; no locality more definite than Queen Charlotte Islands, 1[2].

Mustela erminea anguinae Hall

Ermine

Plates 5, 6, 7, 11, 12 and 13

Mustela cicognanii anguinae Hall, Univ. California Publ. Zoöl., 38:417, November 8, 1932.

Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part).

Putorius streatori, Swarth, Univ. California Publ. Zoöl., 10:102, February 13, 1912.

Mustela erminea anguinae Hall, Journ. Mamm., 26:79, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Type.—Male, adult, complete skeleton (no skin); no. 12482, Mus. Vert. Zoöl., French Creek, Vancouver Island, British Columbia; found as a desiccated carcass on May 1, 1910; obtained by Harry S. Swarth.

Range.—Vancouver Island, British Columbia. See figures 25, 27 pages 95, 149.

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Characters for ready recognition.—Differs from M. e. haidarum, in both sexes, in light-colored underparts less than half the width of dark-colored upper parts, proximal two-thirds of under surface of tail colored like upper parts instead of underparts, interorbital breadth less than distance between glenoid fossa and posterior margin of external auditory meatus; from M. e. fallenda, in both sexes, anterior margin of tympanic bullae flush with squamosal rather than projecting from floor of braincase, in males by sagittal crest absent, in females by total length more than 238 and tooth-rows about same length as, instead of longer than, tympanic bulla; from M. e. streatori, in male, by sagittal crest absent and hind foot ordinarily more than 33.5, in female by hind foot more than 27.5, basilar length more than 30.2; from M. e. olympica, in males, by greater average size, hind foot ordinarily more than 33.4 and interorbital breadth ordinarily more than 8.5, in females by larger size, total length more than 235, tail more than 65, hind foot more than 27.5, basilar length more than 30.2.

Description.—Size.—Male: Sixteen adults and subadults yield average and extreme measurements as follows: Total length, 272 (261-284) mm.; length of tail, 81 (74-86); length of hind foot, 35.0 (33.5-36).

Female: Five adults and subadults have corresponding measurements as follows: 247 (241-257); 69 (66-73); 30.0 (28.0-32.0).

Color.—As described in Mustela erminea streatori except that: occasionally white in winter; upper parts about tone 2 of Dark Chocolate of Oberthür and Dauthenay; least width of color of underparts averaging, in 7 adult males, 6 (0-15) per cent of greatest width of color of upper parts. Black tip of tail in same series averaging 37 (26-46) mm. which is 46 (32-54) per cent of length of tail-vertebrae.

Skull.—Male (based on 13 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.2 (1.0-1.3) grams; basilar length, 34.0 (32.5-35.6); length of tooth-rows more or less (usually less) than length of tympanic bulla.

Female (based on 5 adults): See measurements and plates 11-13. As described in Mustela erminea richardsonii except that: Weight 0.9 (0.77-1.06) grams; basilar length, 31.5 (30.9-31.8) grams; length of tooth-rows more or less than (approximately same as) length of tympanic bulla; breadth of rostrum more than 30 per cent of basilar length.

The sexual dimorphism in the skull is slight, the skull of the male being only a third heavier than that of the female. In fallenda of the adjacent mainland to the east the male is three-fourths heavier than the female. In comparison with fallenda, males are smaller, averaging less in every cranial and dental measurement taken and by weight are a fifth lighter; sagittal crest absent rather than present; tympanic bullae flush with squamosal rather than projecting below floor of braincase; in relation to basilar length, tympanic bullae smaller, braincase deeper and broader, skull wider interorbitally and across zygomata. Females are larger than in fallenda, and with one exception average larger in every cranial and dental measurement taken, being 6 per cent heavier. The one exception mentioned is the lesser actual length of the tympanic bulla in anguinae, in which the length of the tooth-rows is about the same as, rather than less than, the length of the tympanic bulla. The postorbital breadth is greater than in fallenda and the anterior edges of the tympanic bullae are flush with the squamosals rather than projecting below the floor of braincase. In relation to the skull as a whole the preorbital and interorbital parts are larger.

In comparison with streatori, skulls of males are of about the same size, anguinae being only 9 per cent heavier. The length of the tooth-rows is ordinarily less than, rather than about equal to, the length of the tympanic bulla; sagittal crest wanting rather than present since in anguinae the temporal muscles meet usually only at the posterior end of the braincase instead of all along the midline on its top; tympanic bullae narrower and more nearly flush with squamosal (less protruded from braincase). Relative to the basilar length, the zygomatic breadth is more, the tympanic bullae are narrower, and the braincase is deeper at the anterior end of the basioccipital. The female is 41 per cent heavier than streatori, there being no overlap in most cranial and dental measurements. M1, however, is approximately the same size in each subspecies. The tooth-rows and tympanic bulla are of almost equal length whereas in streatori the length of the tooth-rows is less than that of the bulla.

Differences from olympica, in males, are: M1 shorter; all other measurements of teeth and parts of skull averaging larger; skull 20 per cent heavier; tooth-rows averaging shorter than tympanic bulla rather than about the same; relative to basilar length, braincase deeper at anterior end of basioccipital and tooth-rows shorter. The skull of the female is 64 per cent heavier, larger in every measurement taken without overlap; temporal ridges meeting, rather than separated, at lambdoidal crest; length of tooth-rows about equal to, rather than shorter than, tympanic bulla; in relation to basilar length, skull deeper, orbitonasal length more, mastoid and zygomatic breadths more, and tympanic bullae shorter.

Remarks.—References in the literature to this insular race mostly were under the name streatori until 1932 when in the course of the present study the name anguinae was proposed. A few specimens have been taken by nearly every student of small mammals who has collected on Vancouver Island. Arthur Peake and Herbert Laing have probably collected more specimens than any other two zoölogists.

M. c. anguinae is noteworthy for the slight secondary sexual variation in size; the disparity between the two sexes is less than in any other American subspecies of erminea. By linear measurement the body of the female is only 7 per cent shorter than in the male (178 versus 191 mm.). Linear measurements and weights of the skulls of the two sexes are further indicative of this approximation in size. By weight the skull of the female is only a fourth lighter than that of the male, or, stated in another way, the male's skull is only a third heavier (1.2 versus 0.9 grams).

No geographic variation has been detected between lots of specimens from different parts of Vancouver Island. The one specimen available from Salt Spring Island presents no obvious differences from selected individuals from Vancouver Island.

The winter pelage is more often brown than white. Of 17 specimens seen in winter pelage or in transition pelage, only 6 are white. These 6 are from Comox, Stamp River, Hilliers, Jeune Landing and Port Alice. Of the 34 specimens in brown pelage, 7 have the dark color of the upper parts meeting on the abdomen. Six of the 34 have brown color on the pectoral region. In two, this is a separate patch but in the other four the dark color is a continuation of the upper parts and extends in front of each foreleg over part of the pectoral region, but the two extensions, one from either side, do not meet on the underparts. The color of the lips was recorded in 22 individuals: one had both the upper and lower-lips white; 7 had the upper lips brown and the lower lips white; in 14 both the upper and lower-lips were brown.

Specimens examined.—Total number, 40, listed by localities from north to south as follows. Unless otherwise indicated, specimens are in the National Museum of Canada.

British Columbia. Vancouver Island: Cape Scott, 4; Shushartie, 1; Quatsino, 1[74]; Jeune Landing, 1[74]; Port Alice, 5[15]; Marble Creek, Quatsino Sound, 1[22]; Port Hardy, 5; Sayward, 2; Bear Lake, 4; Bear River, 1; Comox, 4(3[85]); Stamp River, Alberni, 1[31]; Errington, 1[74]; French Creek, 1[74]; Hilliers, 1[74]; Craigs Crossing, 1[74]; Nanaimo, 2[22]; Cowichan Lake, 1[22]; Duncan, 2[85]; Salt Spring Island, 1[85].

Mustela erminea fallenda Hall

Ermine

Plates 5, 6, 7, 11, 12 and 13

Mustela erminea fallenda Hall, Journ. Mamm., 26:79, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Putorius streatori Merriam, N. Amer. Fauna, 11:13, June 30, 1896 (part-Sumas).

Fig. 27. Map showing known occurrences and probable geographic ranges of the subspecies of Mustela erminea in Washington and parts of British Columbia and Oregon.

Type.—Male, adult, skull and skin; no. 7096, Nat. Mus. Canada; Huntingdon, British Columbia; May 21, 1927; obtained by C. H. Young, original no. 317.

The brown summer skin is well made. The skull (plates 5-7) is complete. Right p2 has the crown broken away; otherwise the teeth all are present and entire.

Range.—On mainland in immediate vicinity of coast from probably opposite Texada Island, British Columbia, south to Lake Whatcom, Washington, and east to Mount Baker Range on International boundary. See figures 25, 27 on pages 95, 149.

Characters for ready recognition.—Differs from M. e. haidarum, in both sexes, in light-colored underparts less than half the width of dark-colored upper parts, proximal two-thirds of under surface of tail colored like upper parts instead of underparts, interorbital breadth less than distance between glenoid fossa and posterior margin of external auditory meatus; from M. e. richardsonii in both sexes, by upper lips brown rather than white, in males hind foot less than 41 and basilar length less than 38.3, in females hind foot less than 29, basilar length less than 31.4 and breadth of rostrum more, instead of less, than 30 per cent of basilar length; from M. e. invicta, in both sexes, by upper lips brown (not white); in males by skull averaging shorter (basilar length 35.7 versus 37.0); in females by breadth of rostrum more, instead of less, than 30 per cent of basilar length; from M. e. anguinae, in both sexes, by anterior margin of tympanic bulla projecting from floor of braincase rather than flush with squamosal (the difference is slight in females), in males by sagittal crest present, in females by total length less than 238 and tooth-rows longer than, instead of about same length as, tympanic bulla; from M. e. streatori, in both sexes, by black tip of tail more than half of length of tail-vertebrae, in males hind foot more than 33.7, tympanic bulla longer than, instead of about same length as, upper tooth-rows; weight of skull more than 1-1/4 grams, in females weight of skull more than 0.7 grams, length of lateral side of P4, 4 mm. or more; from M. e. olympica, in males, length of hind foot more than 33, black tip of tail more than 36.5 mm., weight of skull more than 1.2 grams, basilar length more than 33.5, in females length of hind foot more than 25.5, weight of skull more than 0.66 grams, basilar length more than 28.4; from M. e. gulosa, in both sexes, by anterior margin of tympanic bulla projecting below floor of braincase rather than flush with squamosal (the difference is slight in females), in males hind foot more than 33.5, weight of skull more than 1-1/4 grams, basilar length more than 33.9, in females by total length more than 222, hind foot longer than 26, weight of skull more than 0.7 grams, basilar length more than 29.

Description.—Size.—Male: Seven adult topotypes yield average and extreme measurements as follows: Total length, 278 (249-305); length of tail, 77 (69-81); length of hind foot, 36.5 (34-40). A male topotype of unknown age weighed 113 grams.

Female: Two adult topotypes, with actual measurements in parentheses, average as follows: Total length, 232 (228-236); length of tail, 60 (57-62); length of hind foot, 27 (27-27). An adult from Morovitz Guard Station, Wash., weighed 54 grams.

[151]

Color.—Winter pelage rarely white, brown pelage indistinguishable from summer pelage except for slightly more smoky tinge in winter in specimens from some localities; otherwise as described in Mustela erminea streatori except that least width of color of underparts averaging, in seven adult topotypes, 18 (0-37) per cent of greatest width of color of upper parts. Black tip of tail averaging, in same series, 45 (38-52) mm. which is 58 (53-65) per cent of length of tail-vertebrae.

In comparison with richardsonii and invicta, fallenda differs in darker color of upper parts and their extension at the expense of the light-colored underparts which are narrower by a half. In correlation with this restriction in area of the light-colored underparts, the upper lips are brown instead of white. In comparison with anguinae, olympica and streatori, the longer black tip on the tail is the principal difference in color. From gulosa, fallenda differs in slightly darker color of upper parts and in narrow underparts, the width of the same being only about a fifth instead of a third of the width of the dark-colored upper parts.

Skull.—Male (based on 7 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.5 (1.3-1.7) grams; basilar length, 35.7 (34.3-38.2).

Female (based on 6 ads.): See measurements and plates 11-13. As described in Mustela erminea richardsonii except that: Weight, 0.85 (0.73-1.0) grams; basilar length, 30.6 (29.4-31.7); breadth of rostrum more than 30 per cent of basilar length.

In comparison with richardsonii, skulls of males differ as follows: averaging smaller in every measurement taken with no overlap in several dimensions; 40 per cent lighter; in relation to basilar length, rostrum (orbitonasal length) longer and skull slightly broader interorbitally. Females average smaller in every cranial and dental measurement taken with no overlap in basilar length, length of tooth-rows and length of tympanic bulla; 22 per cent lighter; breadth of rostrum more, rather than less, than 30 per cent of basilar length; in relation to basilar length, pre- and interorbital parts of skull larger, and mastoid breadth more.

Differences from males of olympica are: size larger with no overlap in most measurements; 50 per cent heavier; tympanic bullae longer than upper tooth-rows rather than of about equal length; in relation to basilar length, rostrum shorter, braincase wider and deeper, zygomata more expanded. Females are larger with no overlap in most measurements; 35 per cent heavier; in relation to basilar length, pre- and interorbital regions narrower, braincase deeper and wider across mastoids.

Differences from streatori, in males, are: skull averaging larger in every cranial and dental measurement taken; 36 per cent heavier; tympanic bulla longer than, instead of about same length as, upper tooth-rows. In females the inner lobe of M1 is shorter anteroposteriorly; otherwise all measurements of fallenda average larger and it is 33 per cent heavier; rostrum and interorbital region broader in relation to remainder of skull.

In comparison with gulosa, skulls of males differ as follows: averaging larger in every measurement taken with no overlap in several dimensions; 50 per cent heavier; tympanic bullae with anterior margins projecting slightly below squamosals rather than flush with same; length of bulla more than, rather than about same as, that of upper tooth-rows. Considering the great difference in size, the relative proportions are remarkably alike. In females, length of inner lobe of M1 about the same; otherwise averaging larger in every measurement taken; 44 per cent lighter; relative to basilar length, tooth-rows longer, skull wider across zygomata and mastoids, rostrum and interorbital regions slightly narrower, skull shallower in plane of last upper molars.

Comparisons with haidarum, invicta and anguinae are made in accounts of those subspecies.

Remarks.—Until the name fallenda was proposed in the course of the present study, most of the specimens of this race were assigned to streatori.

Intergradation with streatori is complete as it is also with invicta and richardsonii, in other words with each of the subspecies whose ranges meet that of fallenda. In color and in size the difference is least between streatori and fallenda. As between fallenda and invicta the size is not greatly different and the intergradation in color is gradual. Between fallenda and richardsonii intergradation is somewhat different and to fully appreciate its nature we should remember that the color of fallenda resembles that of the saturate coastal races, streatori, anguinae and olympica although the black tip of the tail is longer. In this latter feature and in several cranial details, as well as in greater degree of secondary sexual variation in size, fallenda resembles richardsonii. Because the two differ more than do most subspecies of ermine whose ranges meet, some of the intergrades at first inspection appear to be widely different from either parent stock. For example, specimens from Alta Lake, British Columbia, may give this impression because the combination of large size and dark color suggests a kind of ermine different from either fallenda or richardsonii. In no instance, however, has there been found in these intergrades any character other than those occurring in one or the other of the two parent races.

Along the coast in the north part of the geographic range assigned to fallenda, some specimens nearly typical of richardsonii have been taken so near to the place where fairly typical fallenda was obtained that I have doubted whether there is intergradation in the usual fashion in this area; more specimens will have to be obtained from this coastal area to resolve the doubt one way or the other.

The winter pelage is brown in all specimens at most localities. The only white pelage seen was in each of three specimens from Glacier, Whatcom County, Washington. A fourth specimen from there is in brown winter pelage. At any one locality there is much variation in the degree to which the dark color of the upper parts encroaches on the area that in most other races is light-colored. An extreme degree of encroachment is shown by a specimen taken on December 1, 1935, by R. A. Cummings, at Vancouver, British Columbia, in which the light color occurs only in three restricted areas, the chin, the throat and the lower breast; otherwise the coat is brown. There are other specimens, for instance from the type locality, which differ mainly in having an additional white spot in the inguinal region. The opposite extreme, in a specimen also from the type locality, is where the least width of the light-colored underparts on the abdominal region is a third of the circumference of the body. The two extremes are connected by a dozen intermediate stages. Of 64 specimens in which the color of the lips was carefully examined, one, from Vancouver, has both the upper and lower-lips brown; 9 have both the upper and lower-lips white; and 54 have the upper lips brown and the lower lips white.

Specimens examined.—Total number, 72, arranged by localities from north to south. Unless otherwise indicated, specimens are in the National Museum of Canada.

British Columbia. Horseshoe Lake, Stillwater, 2; Vancouver, 1[74]; Point Grey, 1[31]; Port Moody, 5[91]; Chilliwack, 8 (2[75], 4[91], 1[60]); Sumas, 19 (18[75], 1[60]); Thurstons Ranch, 2; Cultus Lake, 2; Mt. Baker Range, 5[75]; Lihumption Park, 1; Huntingdon, 14; Tami Hy Creek, 1.

Washington. Whatcom County: Semiahmoo, 1[91]; New Whatcom, 1[68]; Lake Whatcom, 2[91]; 5 mi. W Glacier, 1[51]; Glacier (3 at 900 ft.), 4[91]; E Side Easton Glacier, Mt. Baker, 1[55]; Morovitz Guard Station, 831 ft., 1[55].

Mustela erminea olympica Hall

Ermine

Plates 5, 6, 7, 12, 13 and 14

Mustela erminea olympica Hall, Journ. Mamm., 26:81, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Mustela rixosa, Svihla and Svihla, Murrelet, 13:24, January, 1932.

Mustela rixosa rixosa, Svihla and Svihla, Murrelet, 14:39, May, 1933.

Type.—Male, adult, skull and skin; no. 90738, U. S. Nat. Mus., Biol. Surv. Coll.; near head of Soleduc River, 4500 ft., Olympic Mountains, Clallam County, Washington; April 28, 1897; obtained by Vernon Bailey, original no. 6213.

The skin is well prepared and in good condition. The skull (plates 5-7) is unbroken and the teeth all are present and entire.

Range.—Olympic Peninsula, Washington, south to Olympia. See figures 25, 27 on pages 95, 149.

Characters for ready recognition.—Differs from M. e. anguinae, in males, by lesser average size, hind foot ordinarily less than 33.4, and interorbital breadth ordinarily less than 8.5, in females by smaller size, total length less than 235, tail less than 65, hind foot less than 27.5, basilar length less than 30.2; from M. e. fallenda, in males, by length of hind foot less than 33, black tip of tail less than 36.5, weight of skull less than 1.2 grams, basilar length less than 33.5, in females length of hind foot less than 25.5, weight of skull less than 0.6 grams, basilar length less than 28.4; from M. e. streatori by smaller size, in males hind foot less than 33.0, basilar length ordinarily less than 32.5, in females by hind foot ordinarily not longer than 24, by breadth of rostrum less than 8.6, depth of braincase at posterior border of upper molars less than 7.6.

Description.—Size.—Male: Twelve individuals of adult proportions yield average and extreme measurements as follows: Total length, 243 (205-269); length of tail, 65 (60-74); length of hind foot, 31 (29-32).

Female: Corresponding measurements of six females are: 196 (188-208), 52 (45-60?), 23.4 (22.7-24.0). An adult weighs 30 grams.

Color.—As described in Mustela erminea streatori except that least width of color of underparts averaging, in 12 males of adult proportions, 5 (0-11) per cent of greatest width of color of upper parts. Black tip of tail averaging, in same series, 26 (20-35) mm., which is 40 (31-58) per cent (average the same as in streatori) of length of tail-vertebrae.

Skull.—Male (based on 5 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.0 (0.9-1.1) grams; basilar length, 31.8 (30.6-32.5); length of tooth-rows more or less than (about equal to) length of tympanic bulla.

Female (illustrated by 3 adults): See measurements and plates 12-14. As described in Mustela erminea richardsonii except that: Weight, 0.55 (0.52-0.58) grams; basilar length, 27.1 (26.7-27.5); breadth of rostrum more than 30 per cent of basilar length.

In comparison with streatori, skulls of corresponding sex average smaller in every measurement taken with no overlap in most of those of females. Exception is to be made for the inner lobe of M1 in males where the size is the same. By weight males are smaller by 10 per cent and females by 14 per cent. In relation to other parts of the skull the tympanic bullae are narrower and in females they are shorter as well. Comparison with anguinae and fallenda has been made in the accounts of those subspecies.

Remarks.—The smaller size, especially of females, is the principal feature distinguishing this race from streatori. On the basis of available data the female of olympica is smaller than that of any other race and hence is the smallest adult weasel of the species erminea, in either the Old World or in America.

Intergradation with streatori is indicated by specimens from the southern end of Puget Sound. These specimens are intermediate in size between typical examples of the two races concerned.

The color of the upper parts is uniform and the color pattern varies less than in geographically adjoining races. The white color of the underparts is restricted to a thin line on the abdominal region, but widens out posteriorly in the inguinal region and anteriorly over the pectoral region, throat, chin and lower lips. The upper lips are brown. The brown of the upper parts extends around in front of each foreleg, the two brown areas not quite meeting on the lower throat. The above description applies to each of the 19 specimens examined with regard to these details. Every specimen seen in the winter coat was brown, not white.

Specimens examined.—Total number, 20, arranged by counties from north to south. Unless otherwise indicated, specimens are in the U. S. National Museum.

Washington. Clallam County: Clallam Bay, 2 (1[74], 1[94]); Elwha, 2[10]; Johnsons Ranch, 1[60]; Happy Lake, 1[60]; Boulder Lake, 2[60]; near head of Soleduc River, 4500 ft., 1; 12 mi. S Port Angeles, 1[10]. Jefferson County: Hayes Cr., 2000 ft., Elwha River, 2; head N Fork Quinault River, 4000 ft., 1; Duckabush, 3; N Fork Skokomish River, 1. Mason County: Lake Cushman, 2[76]; 4 mi. S Olympia, 1.

Mustela erminea streatori (Merriam)

Ermine

Plates 5, 6, 7, 12, 13 and 14

Putorius streatori, Merriam, N. Amer. Fauna, 11:13, pl. 2, figs. 5, 5a, 6, 6a, June 30, 1896.

Putorius cicognanii, Baird, Mamm. N. Amer., p. 161, 1858 (part unless no. 2395 was a female of M. frenata).

Putorius pusillus, Baird, Mamm. N. Amer., p. 159, 1858 (part).

Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877 (part).

Mustela streatori streatori, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Grinnell, Univ. California Publ. Zoöl., 40:101, September 26, 1933.

Mustela cicognanii streatori, Hall, Murrelet, 12:22, January, 1931; Hall, Univ. California Publ. Zoöl., 38:417, November 8, 1932.

Mustela erminea streatori, Hall, Journ. Mamm., 26:77, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Mustela rixosa, Beer, Journ. Mamm., 29:296, August 31, 1948.

Type.—Male, adult, skull and skin; no. 76646, U. S. Nat. Mus., Biol. Surv. Coll.; Mount Vernon, Skagit Valley, Skagit County, Washington; February 29, 1896; obtained by D. R. Luckey, original no. 3.

The skull is unbroken and the teeth all are present and entire. The skin, in brown winter pelage, is stuffed and in good condition.

Range.—Western Washington along eastern side of Puget Sound, western Oregon from the Cascades to the coast, and northwestern California south in the humid coastal district nearly to the Golden Gate. See figures 25, 27 on pages 95, 149.

Characters for ready recognition.—Differs from M. e. anguinae, in male, by sagittal crest present and hind foot ordinarily less than 33.5, in female by hind foot less than 27.5, basilar length less than 30.2; from M. e. fallenda, in both sexes, by black tip of tail less than half of length of tail-vertebrae, in males hind foot less than 33.7, tympanic bulla about same length as, instead of longer than, upper tooth-rows; weight of skull less than 1-1/4 grams, in female weight of skull less than 0.7 grams, length of lateral side of P4 less than 4 mm.; from M. e. olympica, by larger size, in males hind foot more than 33.0, basilar length ordinarily more than 32.5, in females by hind foot ordinarily longer than 24, by breadth of rostrum more than 8.6, depth of braincase at posterior border of upper molars more than 7.6; from M. e. gulosa and muricus, in both sexes, by upper lips brown (not white), light color of underparts extending down hind leg no farther than knee, depth of skull at posterior border of upper molars more than 7.7 in females and ordinarily more than 9.6 in males, further from muricus by tail more than 62 in males and more than 49 in females; from M. e. invicta by upper lips white (not brown), in males hind foot more than 36 and basilar length more than 35, in females hind foot more than 29.5 and basilar length more than 30.5.

Description.—Size.—Male: Twelve adults from Blaine and Tillamook, Oregon, yield average and extreme measurements as follows: Total length, 255 (245-275); length of tail, 72 (64-80); length of hind foot, 31.5 (30.0-33.5).

Female: Seven adults from Blaine and Tillamook, Oregon, yield average and extreme measurements as follows: Total length, 214 (193-230); length of tail, 55 (50-63); length of hind foot, 25 (24-27).

Color.—Winter and summer pelages indistinguishable; upper parts uniform and ranging from Raw Umber to slightly darker (16n), and about tones 1 to 3 of Dark Chocolate of Oberthür and Dauthenay, pl. 342; underparts white, in summer rarely with a faint buffy suffusion in pectoral region; color of underparts extends from chin, and often lower lips, posteriorly to inguinal region, distally on posterior sides of forelegs onto antipalmar faces of toes (sometimes interrupted at and above wrist) and on medial sides of hind legs hardly to knee. Least width of color of underparts averaging, in twelve adults from Blaine and Tillamook, 10 (0-47) per cent of greatest width of color of upper parts. Black tip of tail, in same series, averaging 28 (24-33) mm. which is 40 (34-47) per cent of length of tail-vertebrae.

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Skull.—Male (based on 12 adults): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.1 (1.0-1.2) grams; basilar length, 33.2 (32.5-33.8); length of tooth-rows more or less than (about same as) length of tympanic bulla.

Female (based on 7 adults): See measurements and plates 12-14. As described in Mustela erminea richardsonii except that: Weight, 0.64 (0.60-0.67) grams; basilar length, 28.5 (27.6-29.5); breadth of rostrum more than 30 per cent of basilar length.

Comparison with anguinae, fallenda, olympica, gulosa and muricus is made in accounts of those subspecies.

Remarks.—This weasel is rare in collections and the best material of it was obtained by Alex Walker in Tillamook County, Oregon, where he resides. The almost ideal series of 30 specimens showed the range of secondary sexual, age, and individual variation expectable in the small ermines of the Pacific Coast of the United States and was the means of allowing satisfactory decision on questions of classification in the related subspecies in which individuals are of comparable size.

Intergradation with each of the geographically adjoining subspecies, olympica, fallenda, invicta, gulosa and muricus is shown by specimens examined. With the last mentioned subspecies, intergradation is shown by two specimens from as far south as Siskiyou County, California, assigned to muricus.

The application of the name streatori is difficult because it was based on a specimen from a place where two clines cross. The north-south cline is one of size which decreases to the south. The east-west cline is one of intensity of color, the westernmost (coastal) population being the most intensely colored. The type locality of streatori is at the place where two lines perpendicular to one another, and representing the two clines, cross. This intersection is near the place where the ranges of several subspecies meet. The nomenclatural question is, to which one of 6 subspecies should the name streatori apply. Specimens from barely within the geographic boundaries of four of these subspecies so closely resemble topotypes of streatori that a student with material at his disposal from only the area about Puget Sound naturally would apply the name streatori to all of his specimens, and knowing even of the arrangement adopted in the present account the student will have difficulty in identifying his specimens according to it. Not only will the student find the arrangement difficult, but probably unsatisfactory if he thinks of streatori as being the kind of animal represented by topotypes. I conceive of topotypes of streatori as being nontypical of the subspecies; they are intergrades with fallenda. My aim was initially to work out the geographic ranges of subspecies and only subsequently to apply names, according to which type localities fell within the previously determined geographic ranges. By this procedure no greater weight was given to a holotype and to topotypes than to specimens from any other locality.

Of the 40 specimens seen in winter pelage, only one is white. It is from Darrington in the Cascade Mountains of Washington. The 39 others are brown and I doubt that the white pelage ever occurs in the low coastal territory included within the geographic range of streatori. This subspecies resembles anguinae and olympica in the great extension of area of the dark-colored upper parts at the expense of the area of the light-colored underparts. The usual arrangement is one where the brown of the two sides nearly meets on the midventral line leaving a sizable, inguinal area of light color connected by a thin line to the sizable area of light color on the pectoral region. The light color of the pectoral area ordinarily is continuous with the light-colored area of the throat and chin but the dark color of the upper parts extends around in front of each foreleg. These extensions of dark color meet on the chest in only 2 of the 56 specimens examined in this regard. Across the abdomen the dark color is continuous in 4 of the 56 specimens. The lower lips are brown instead of white in only 3 individuals and in 2 of these the lip of one side is brown and its opposite is white. The variation in color-pattern is less than in anguinae or than in fallenda.

Specimens examined.—Total number, 63, arranged alphabetically by states, then by counties from north to south in each state. Unless otherwise indicated, specimens are in the U. S. National Museum.

California. Humboldt County: 10 mi. NE Carlotta, 1[74]. Mendocino County: Russian Gulch State Park, 1[74]. Sonoma County: Mouth of Gualala River, 1[74].

Oregon. Clatsop County: Astoria, 1. Tillamook County: Tillamook, 16 (14[14], 1[59]); Blaine, 12 (7[14], 2[59], 1[93], 2[76]). Washington County: Beaverton, 1[60]; Forest Grove, 1[36]. Clackamas County: Oregon City, 1[46]. Lincoln County: Newport, 1. Linn County: Sico, 1[46]. Lane County: Vida Fish Hatchery, 2[101]; McKenzie Bridge, 1[101]; Mercer, 1[75]. Klamath County: Deschutes River, 6 mi. E Crescent Lake, 1[101]. Douglas County: Gardiner, 1[60]. Curry County: Port Orford, 1; Gold Beach, 2[60].

Washington. Skagit County: N end Whidby Island opposite Deception Pass, 1; Hamilton, 4; Mt. Vernon, 3. Snohomish County: Oso, 550 ft., 1; Darrington, 600 ft., 1. Pacific County: Wallicut River, 2 mi. E Ilwaco, 1[74]. Wahkiakum County: 4 mi. E. Skamokawa, 3[74]. Cowlitz County: 4 mi. E mouth Kalama River, 2[74]; 6 mi. E mouth Kalama River, 1[74]. Skamania County: 15 mi. N Govt. Springs, 1300 ft., 1.

Mustela erminea gulosa Hall

Ermine

Plates 5, 6, 7, 12, 13 and 14

Mustela erminea gulosa Hall, Journ. Mamm., 26:84, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Putorius streatori Merriam, N. Amer. Fauna, 11:14, June 30, 1896.

Type.—Male, subadult, skull and skin; no. 81998, U. S. Nat. Mus., Biol. Surv. Coll.; Trout Lake, Klickitat County, Washington; February 3, 1897; obtained by P. Schmid, original no. 147.

The skin is in brown winter pelage, and appears to have been made up from a skin split along the midventral line from the anus to the forelegs. It probably was dried by a trapper, is well made, and lacks a patch of hair on the left flank but otherwise is in good condition. The skull lacks the central part of the left zygomatic arch and the posterior two-thirds of the right one. The right m2 is represented only by an abortive stump or the broken root, and i1 and i2 on each side are absent; otherwise, the teeth all are present and entire.

Range.—Cascades of Washington from northeastern King County south to Mount Adams. See figures 25, 27 on pages 95, 149.

Characters for ready recognition.—Differs from M. e. invicta and fallenda, in both sexes, by anterior margin of tympanic bulla flush with squamosal rather than projecting below floor of braincase (difference slight in females), in males hind foot less than 33.5, weight of skull less than 1-1/4 grams, basilar length less than 33.9, in females by total length less than 222, hind foot shorter than 26, weight of skull less than 0.7 grams, basilar length less than 29; from M. e. muricus, in both sexes, by upper parts darker, tone 4 of Chocolate or darker (see description of color), least width of light-colored underparts averaging one-third instead of approximately two-thirds of greatest width of dark-colored upper parts, in males, on the average, tail more than 65, weight of skull more than 0.90 grams, basilar length more than 30.8 mm.; from M. e. streatori, in both sexes, by upper lips white (not brown), light color of underparts extending down hind legs below knee, depth of skull at posterior border of upper molars less than 7.7 in females and ordinarily less than 9.6 in males.

Description.—Size.—Male: One adult and four subadults from Mount Rainier yield average and extreme measurements as follows: Total length, 253 (238-266); length of tail, 75 (70-83); length of hind foot, 31.5 (30-33). Corresponding measurements of 9 subadults from Trout Lake are: 257 (233-282); length of tail, 76 (56-83); length of hind foot, 30.2 (26-33).

Female: Of adults, 2 from Mount Rainier and 2 from Trout Lake measure as follows: Total length, 202, 203, 216, 210; length of tail, 54, 52, 57, 51; length of hind foot, 24, 24, 25, 24. The averages for these females are 208, 54, 24.3.

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Color.—As described in Mustela erminea richardsonii except that color sometimes brown in winter (with more smoky tinge than summer coat); upper parts ranging from tone 2 through tones 3 and 4 of Dark Chocolate (pl. 342) into tone 4 of Chocolate (pl. 343) of Oberthür and Dauthenay; underparts (always white in winter) in summer Sulphur Yellow or more whitish; least width of color of underparts averaging, in 5 males from Mount Rainier, 31 (18-45) per cent of greatest width of color of upper parts. Black tip of tail, in same series, averaging 34 (29-40) mm., which is 45 (41-50) per cent of length of tail-vertebrae.

Skull.—Male (based on 2 ad. and 13 sad.): See measurements and plates 5-7. As described in Mustela erminea richardsonii except that: Weight, 1.0 (0.95-1.16) grams; basilar length, 32.3 (30.9-33.4); length of tooth-rows more or less than (about equal to) length of tympanic bulla.

Female (illustrated by 5 adults): See measurements and plates 12-14. As described in Mustela erminea richardsonii except that: Weight, 0.59 (0.53-0.65) grams; basilar length, 28.1 (27.8-28.4); breadth of rostrum ordinarily more than 30 per cent of basilar length.

In comparison with streatori, skulls of males and females average smaller in every cranial measurement taken. Teeth of about same size and males 9 per cent, and females 8 per cent, lighter. In relation to basilar length, skull of female shallower, tympanic bullae slightly shorter and, on the average, zygomata less expanded.

In comparison with muricus, males average larger in every measurement taken; 23 per cent heavier; in relation to other dimensions, braincase shallower at anterior end of basioccipital. Females are of about equal size; in relation to other dimensions, braincase shallower and mastoid and zygomatic breadths less.

Comparisons with invicta and fallenda have been made in the accounts of those subspecies.

Remarks.—This is not a strongly marked race and in most of the characters used for differentiating it from other races it resembles either streatori to the west or muricus to the southeast. Nevertheless, there is a geographic area, the southern Cascades of Washington, throughout which individual characters are combined in essentially the same way and there are a few features, for instance, smaller skull of the female, in which gulosa differs from either of its close relatives. In view of these circumstances and because the animals can not well be included in the subspecies streatori or muricus, gulosa is recognized as distinct. The races gulosa and olympica are what might be termed weakly differentiated subspecies in contrast to the strongly differentiated subspecies streatori and muricus.

Of the 21 specimens in winter pelage, 17 are white and four are brown. The brown winter coat is distinctly paler, with more of a smoky tinge, than the brown summer pelage. The light-colored underparts are narrower than in the subspecies immediately to the east but are wider than in the coastal forms to the west. The dark color of the upper parts extends onto the chest in front of the forelegs, as in the coastal forms, in only one of the 13 specimens in summer pelage and in it on one side only. The black tip of the tail is short as in the coastal forms. One specimen is in transitional pelage. It has acquired approximately half of the white winter pelage and was taken on October 12, 1897, at Keechelus Lake.

Specimens examined.—Total number, 38, arranged by counties from north to south. Unless otherwise indicated, specimens are in the U. S. National Museum.

Washington. King County: 2 mi. E Skykomish, 2[51]. Kittitas County: Keechelus Lake, 3 (1[1]); Martin, 1[1]; Easton, 3. Pierce County: James Lake, 4370 ft., Mt. Rainier, 1; Glacier Basin, 5935 ft., Mt. Rainier, 1; Meslers Ranch, 2000 ft., 1 mi. W Rainier Park, 1. Lewis County: Mt. Rainier Nat'l Park, 5 (1 each from: Paradise Park, 5400 ft.; Reflection Lakes, 4900 ft.; Ohanapecosh [Hot] Springs, 2000 ft.; Tahoma Creek, 1[72]; Bear Prairie); also in Mt. Rainier Nat'l Park, Longmire, 3 (1[72], 1[94]). Skamania County: Mt. St. Helens, 6000 ft., 1. Klickitat County: Trout Lake, 18.

Mustela erminea muricus (Bangs)

Ermine

Plates 7, 8, 12, 13, 14 and 41

Putorius (Arctogale) muricus Bangs, Proc. New England Zoöl. Club, 1:71, July 31, 1899.

Putorius streatori leptus Merriam, Proc. Biol. Soc. Washington, 16:76, May 29, 1903. Type from Silverton, San Juan County, Colorado.

Putorius muricus, Stephens, California Mammals, p. 248, 1906.

Putorius cicognani, Taylor, Univ. California Publ. Zoöl., 7:298, June 24, 1911.

Mustela streatori leptus, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Bailey, N. Amer. Fauna, 35:48, September 5, 1913; Dixon, Journ. Mamm., 12:72, February 12, 1931; Whitlow and Hall, Univ. California Publ. Zoöl., 40:246, September 30, 1933.

Mustela muricus, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Kellogg, Univ. California Publ. Zoöl., 12:358, January 27, 1916.

Mustela cicognanii lepta, Dice, Journ. Mamm., 1:12, November 28, 1919; Hall, Mamm. Nevada, p. 184, July 1, 1946.

Mustela rixosa, Seton, Journ. Mamm., 14:70, February 14, 1933.

Mustela cicognanii leptus, Miller, Journ. Mamm., 14:368, November 13, 1933; Bailey, N. Amer. Fauna, 55:293, August 29, 1936.

Mustela erminea murica, Hall, Journ. Mamm., 26:84, February 27, 1945; Hall, Journ. Mamm., 26:181, July 19, 1945.

Type.—Male, young, skull and skin; no. 9146, collection of E. A. and O. Bangs in Mus. Comp. Zoöl.; Echo, 7500 ft., El Dorado County, California; July 15, 1897; obtained by W. W. Price and E. M. Nutting.

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The skull has a fracture along the sagittal suture and fractures on the left side of the braincase but these have been glued, and no part of the skull is missing except in the region of the right P4 which part has been shot away. On the left side m2 never developed. Excepting this tooth and the right P4, all the teeth are present and entire. The skin is well made but has the soles of the hind feet turned up.

Range.—Near 5300 feet (Denver) to 11000 feet (Santa Fe Baldy); typically boreal but taken in Upper Sonoran Life-zone in winter at Denver; from central and southwestern Montana, southern Idaho, and Blue Mountains of southeastern Washington southward east of the Cascade Divide through the Salmon River Mountains and Sierra Nevada at least into Fresno County of California, in the Great Basin to central Nevada, in the Rocky Mountains into northern New Mexico; eastward to the Black Hills. See figure 25 on page 95.

Characters for ready recognition.—Differs from M. e. invicta by hind foot less than 36 and basilar length less than 35 in males and by hind foot less than 29.5 and basilar length less than 30.5 in females; from M. e. gulosa, in both sexes, by upper parts lighter, tone 2 of Chocolate or lighter (see description of color), least width of light-colored underparts averaging about two-thirds instead of one-third of greatest width of dark-colored upper parts, in males, on the average, tail less than 65, weight of skull less than 0.90 grams, basilar length less than 30.8 grams; from M. e. streatori, in both sexes, by upper lips white (not brown), light color of underparts extending down hind leg below knee, depth of skull at posterior border of upper molars less than 7.7 in females and ordinarily less than 9.6 in males, tail less than 62 in males and less than 49 in females.

Description.—Size.—Male: An adult from Black Butte, California, measures: Total length, 227; length of tail, 55; length of hind foot, 27. Corresponding measurements of another from Wheeler Peak, Nevada, are: 220, 56, 26. Two subadults from Colorado, one from Crested Butte and another from Coventry, measure, respectively, as follows: 238, 227; 66, 60; 30, 30. An adult from Wheeler Peak, Nevada, weighs 57.7 grams and another from 2 mi. W Black Butte, Calif., 54.5 grams.

Female: Two adults from Teton County, Wyoming, measure: Total length, 205, 200; length of tail 52,—; length of hind foot, 23, 23.7. A subadult from 9-1/2 mi. E Pocatello, Idaho, measures: 197, 50, 25. An adult from Wheeler Peak, Nevada, has corresponding measurements of 190, 42, 23, and weighs 33.8 grams.

Color.—As described in Mustela erminea richardsonii except that upper parts tone 2 or lighter of Chocolate of plate 343 of Oberthür and Dauthenay; underparts white, Pale Buff or with faint wash of Sulphur Yellow; least width of color of underparts in male from Black Butte and one from Wheeler Peak, amounting to 65 and 59 per cent of greatest width of color of upper parts. Black tip of tail, respectively, 28 and 33 mm., which amounts to 51 and 59 per cent of length of tail-vertebrae. In two adult females, one from Teton County, Wyoming, and one from Wheeler Peak, Nevada, the least width of the underparts amounts to 55 and 60 per cent of the greatest width of color of upper parts. Black tip of tail, respectively, 23 and 19 mm., which amounts to 44 and 45 per cent of length of tail-vertebrae.

From the other subspecies of small-sized weasels of more northwestern occurrence, namely anguinae, fallenda, olympica, streatori and gulosa, muricus differs in lighter color of upper parts, wider light-colored underparts and relatively longer black tip of tail.

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Skull.—Male (illustrated by 5 adults in table of measurements, which see): See plate 7. As described in Mustela erminea richardsonii except that: Weight, 0.78 (Wheeler Peak) and 0.85 (Black Butte) grams; basilar length, 30.6 (29.8-31.2); length of tooth-rows more or less than (approximately equal to) length of tympanic bulla.

Female (illustrated by 6 adults in table of measurements, which see): See plates 12-14. As described in Mustela erminea richardsonii except that: Weight, 0.60 (0.575-0.645); basilar length, 28.0 (27.3-29.4); breadth of rostrum approximately 30 per cent of basilar length.

In comparison with streatori, males average smaller in every measurement taken with no overlap in most dimensions; 25 per cent lighter; anterior margin of tympanic bulla more nearly flush with squamosal, that is to say less protruded from braincase; in relation to other dimensions of skull, braincase shallower anteriorly (at plane of last molars) and deeper posteriorly (at anterior end of basioccipital). Females average smaller in every measurement taken except mastoid and zygomatic breadths which are actually more; 6 per cent lighter; in relation to other parts of skull, preorbital and interorbital parts slightly smaller; in relation to length of skull, braincase shallower. Comparison with invicta and gulosa is made in the accounts of those subspecies.

Remarks.—The smallest males of the entire species are of this subspecies and the females of it are barely larger than those of olympica and gulosa and hence are among the three smallest. The material now available consists only of one or a few specimens from each of several widely separated localities. If as many specimens per unit area were available as there are of the species M. erminea from southern British Columbia, geographic variation warranting the division of muricus into more than one subspecies might be revealed. Evidence pointing in this direction is comprised in the pale color and small size of the pair of adults from Wheeler Peak on the eastern border of Nevada; the suggestion is that there is a distinct pale race of small individuals in the isolated spots of boreal life-zone in the mountains of the desert. The color and size of the specimens from the Toyabe Mountains, and that from the Pine Forest Mountains, both places also in Nevada, nevertheless, lend no support to this suggestion. Comparison of specimens from the Rocky Mountains of Colorado with those from the Sierra Nevada of California gives no basis for recognizing more than one subspecies. Therefore, Putorius streatori leptus Merriam with type locality at Silverton, San Juan County, Colorado, falls as a synonym of the earlier named Putorius (Arctogale) muricus Bangs with type locality at Echo, El Dorado County, California. Furthermore, specimens from northern New Mexico, the southernmost known area of occurrence for the subspecies (and for the species), are as large as specimens from far north in the range of the subspecies, say, in northwestern Wyoming; there is therefore no evidence of progressive decrease in size to the southward as in advance of study I supposed existed in muricus. This erroneous supposition was held because I knew that there was a decrease in size to the southward in the species as a whole and also in each of the subspecies richardsonii and invicta directly to the north of muricus.

Intergradation with invicta is shown by specimens from southwestern Montana. Where the margins of the geographic ranges of invicta and muricus approach one another elsewhere, low-lying territory, zonally unsuited to the existence of the species, occurs along the Snake and Columbia rivers, and precludes any chance of intergradation except around the head of the Snake River Plains. Two specimens, here referred to muricus, from Siskiyou County, California, in both color and cranial characters, are intergrades with streatori and might be referred with almost equal propriety to streatori.

Specimens examined.—Total number, 52, arranged alphabetically by states, then by counties from north to south within each state. Unless otherwise indicated, specimens are in the Museum of Vertebrate Zoölogy, University of California at Berkeley.

California. Siskiyou County: head of Rush Creek, 6400 ft., 1; Castle Lake, 5434 ft., 1. Tehama County: 2 mi. W Black Butte, 6800 ft., 1. Placer County: ridge W of Tahoe Pines, Lake Tahoe, 1; Blackwood Creek, 6250 ft., near Tahoe Pines, 1. El Dorado County: Fallen Leaf Lake, 6500 ft., 1[33]; Echo, 1[75]. Tuolumne County: Ten Lakes, 9200 ft., Yosemite Park, 1. Mariposa County: Vogelsang Lake, 10350 ft., Yosemite Park, 1. Mono County: Mammoth, 1[59].

Colorado. Rio Blanco County: Marvine, 1. Boulder County: Camp Albion, 10600 ft., 1[60]; Boulder, 1[91]. Denver County: Denver, 1[57]. Park County: Jefferson, 1[57]. Gunnison County: near Placita in Gunnison County, 1[26]; Crested Butte, 9000 ft., 3 (1[91], 2[19]). El Paso County: Turkey Creek, SW Colorado Springs, 6000 ft., 1[19]. Chaffee County: Arbourville, 1[91]; Hancock, 1. Montrose County: Coventry, 6800 ft., 1[19]. San Juan County: Silverton, 1[91]; in San Juan County above timberline, 1[87].

Idaho. Bannock County: West Fork of Rapid Creek, 9-1/2 mi. E Pocatello, 1.

Montana. Meagher County: Camas Creek, Big Belt Mts., 4 mi. S Ft. Logan, 1[91]. Beaverhead County: Donovan, 1[91]. County in question: Yellowstone Park, 1[75].

Nevada. Humboldt County: Alder Creek, 6000 ft., Pine Forest Mts., 1. Ormsby County: 1/2 mi. S Marlette Lake, 8150 ft., 1. Nye County: South Twin River, Toyabe Mts., 1[91]. White Pine County: Baker Creek (8500 ft., 8675 ft., 11100 ft.), 3.

New Mexico. Taos County: Twining, 10700 ft., 1[91]. Sandoval County: 9 mi. E Cuba, 9000 ft., 1. Santa Fe County: Saddle S of Santa Fe Baldy, 11000 ft., Santa Fe Range, 1[1].

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Oregon. Wasco County: Mill Creek, 20 mi. W Warmsprings, 1[91]. Klamath County: Fort Klamath, 1[91].

South Dakota. Pennington County: 4 mi. SE Hill City, 5300 ft., 2[76]; Pfander's Ranch, 3 mi. SSE Hill City, 5300 ft., 1[76]; Palmer Gulch, 3 mi. SE Hill City, 5300 ft., 1[76]; Spring Creek, 2 mi. W Oreville, 5500 ft., 1[76]. Custer County: 1/2 mi. E Sylvan Lake, 6250 ft., 1[76].

Washington. Columbia County: Butte Creek, 1; Stayawhile Spring, 5150 ft., 1.

Wyoming. Crook County: 5 mi. NW Sundance, 5900 ft., 1[93]. Teton County: Whetstone Creek, 2[76]; 1/4 mi. E Moran, 6700 ft., 1[93]. Sublette County: 1/2 mi. NE Pinedale, 7500 ft., 1[93]. Albany County: 30 mi. N and 10 mi. E Laramie, 6560 ft., 1[93]; 26 mi. N and 4-1/2 mi. E Laramie, 6960 ft., 1[93]. Carbon County: 8 mi. N and 19-1/2 mi. E Savery, 8800 ft., 2[93].

Mustela erminea? angustidens (Brown)

Plates 7, 12, 13 and 14

Putorius cicognanii angustidens Brown, Mem. Amer. Mus. Nat. Hist., 9 (pt 4):181, pl. 17, 1908.

Mustela cicognanii angustidens, Hay, Iowa Geol. Surv. Bull., 23:32, 1914; Hay, Carnegie Inst. Washington, Pub. no. 322A:252, October 15, 1924; Hay, ibid., Pub. no. 390 (vol. 2): 528, 1930; Hall, ibid., Pub. no. 473:111, 112, November 20, 1936.

Type.—Female, adult, skull and lower jaws lacking zygomata, right P2 and incisors, no. 12432, Amer. Mus. Nat. Hist.; from Conard Fissure, four miles west of Willcockson, Newton County, Arkansas; obtained sometime in the period 1903 to 1905 inclusive (see plates 8, 14).

Range.—Known only from the Pleistocene deposit in Conard Fissure, at the type locality in northern Arkansas.

Description.—Skull.—Male (based on nos. 12437, 12441 and 12444): See measurements and plates 7 and 8; weight, unknown; basilar length, 38.1 (36.6-39.2); length of tooth-rows more than length of tympanic bulla; breadth of rostrum measured across lacrimal processes less than a third of basilar length; interorbital breadth ordinarily equal to distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth probably averaging approximately the same as distance between last upper molar and jugular foramen.

Female (based on nos. 11766 and 12435): See measurements and plates 8, 12-14; weight, unknown; basilar length, 34.0 (32.5-35.1); length of tooth-rows more than length of tympanic bulla; breadth of rostrum about equal to (more or less than) 30 per cent of basilar length; interorbital breadth less than distance between glenoid fossa and posterior border of external auditory meatus; zygomatic breadth probably less than distance between last upper molar and jugular foramen.

Comparison of the cranial description given above with those of the American races of erminea from the far north will show that many characters are held in common—more than with more southern subspecies of erminea.

Remarks.—The ten specimens studied by the writer fall into two groups of six larger individuals and four smaller. Upon comparing these with each sex of the three species of American Recent weasels, frenata, erminea and rixosa, it is seen that size, and to some degree shape, rule out of consideration both sexes of rixosa and also males of frenata. Thus we are left with females of frenata and males and females of erminea. So far as size is concerned, it can be assumed that the larger specimens are females of frenata and that the smaller are males of erminea. This assumption has in its favor also, the fact that the postglenoidal length of the skull accords with that in Recent specimens. The difference in this regard in Recent animals is that the postglenoidal length of the skull, expressed as a percentage of the total (condylobasal) length of the skull, amounts to:

In the fossils the percentage for the larger skulls is 46; for the smaller skulls it is 48.

It may be that the ten fossil skulls are six female frenata and four male erminea but I think not. In the first place a skull of different shape, seemingly of the frenata stock, is known from the deposit and it is almost certain that two subspecies of the same species would not occur at the same place at the same time. It is possible, of course, that parts of the deposits were laid down at times so far apart that a shift in geographic range of two subspecies had occurred. This one skull, seemingly of the frenata stock, is the type of Putorius gracilis Brown (see p. 404) and was regarded as the only known specimen of gracilis. Regardless of the specific identity of this one specimen named gracilis, the chances of obtaining otherwise from a deposit, like that in Conard Fissure, six females of frenata and four males of erminea without a male frenata or a female of erminea coming to light are so slight as strongly to incline me to the view that the six larger specimens are males of the same species to which the 4 smaller specimens belong. By either this interpretation, or the one initially considered (of female frenata and male erminea), the animals from the fissure are at least subspecifically distinct from any American Recent weasel. Furthermore, by this latter interpretation each sex of this weasel, angustidens, is intermediate between the frenata and erminea stocks in the feature of postglenoidal length which feature, at any place where the two Recent species occur together, serves to distinguish one from the other. In the northernmost subspecies of erminea (arctica for example) the postglenoidal length in some males is no longer than in males of frenata. Considering general size, angustidens agrees better with erminea than with frenata and this circumstance has influenced me to place angustidens as a subspecies of erminea.

Today, erminea is not known to occur nearer Conard Fissure than northern Iowa, more than 400 miles to the northward. In comparison with the race there, bangsi, males of angustidens are of approximately the same size but in the shorter distance between the glenoid fossa and anterior margin of the tympanic bulla, and also in the lesser postglenoidal length of the skull, angustidens resembles the northernmost American subspecies of erminea. Females of angustidens differ more from any living weasel than the males do. The females are much larger than those of bangsi, and among living American races of erminea most closely resemble intergrades between arctica and richardsonii which intergrades are found approximately 1700 miles to the north of Conard Fissure. In females, the preorbital part of the skull in M. e. arctica is broader and in M. e. richardsonii narrower than in angustidens. If it seems strange that females of angustidens resemble one subspecies whereas males, in size, resemble another subspecies almost a thousand miles distant, it should be remembered that the degree of sexual dimorphism varies much from one subspecies to another in the Recent animals. An example is furnished by Mustela erminea fallenda and Mustela erminea invicta.

The assemblage of mammals from Conard Fissure includes several species of boreal predilections which, like Mustela erminea, now occur only much farther north than Arkansas. At one time the edge of the sheet of ice was only about 200 miles north of Arkansas. It may be significant that the cranial characters of the female ermine from the Fissure, and qualitative cranial characters of males from there, are most nearly approximated among Recent weasels by those which live along the southern edge of the frozen tundra.

In view of what has been said, the possibility should be considered that the distinctive cranial features of angustidens may be the result of evolutionary change in time as well as of geographic variation resulting from horizontal placement.

MUSTELA RIXOSA (Bangs)

Least Weasel

(Synonymy under subspecies)

Type.—Putorius rixosus Bangs, Proc. Biol. Soc. Washington, 10:21, February 25, 1896.

Range.—From Norway and Switzerland eastward through Siberia and all the way across North America, but unknown from Iceland, Greenland and the Arctic islands west of Greenland; in North America, from the Arctic Life-zone south to Central British Columbia, Montana and into parts of the Upper Austral Life-zone as in the eastern half of the continent.

The southern extension of range in the Appalachians (to North Carolina) is not duplicated in the Rocky Mountains of western North America probably because the region there suitable for rixosa south of Central British Columbia and Montana is occupied by the almost equally small Mustela erminea muricus and related subspecies which seem to fill the ecological role that rixosa plays where it occurs. The small size of females of M. erminea cicognanii in New England may similarly account for the absence of rixosa there.

Characters for ready recognition.—Differs from both Mustela erminea and Mustela frenata by tail a fourth or less of length of head and body and without a black tip (at most a few black hairs at extreme tip in rixosa), and from M. frenata and from M. erminea in regions where it and rixosa occur together, by basilar length of skull less than 32.5 in males and less than 31.0 in females.

Characters of the species.—Size small: Total length less than 250 in males and 225 in females; tail a fourth or less of length of head and body, and without a black pencil and at most with a few black hairs at extreme tip; caudal vertebrae 11 to 16, normally 15 in M. r. rixosa, and 11 in one M. r. eskimo examined; skull with long braincase and short precranial portion, thus essentially same shape as in M. erminea but the largest males of M. rixosa always with a lesser basilar length that even the smallest females of M. erminea or M. frenata of the same geographic area. In fact no specimens of M. frenata have skulls so small as the largest M. rixosa, and skulls of equal size of M. erminea and M. rixosa, for example, M. erminea muricus of Colorado and M. rixosa eskimo of Alaska, differ in that when the skulls are viewed from directly above those of rixosa have the mastoid processes more prominent, or the braincase is higher in relation to its width or both differences together prevail. Stated in another way, comparison of skulls of equal size of rixosa and erminea shows that in the latter the braincase is more nearly flat and is wider above and in front of the mastoid processes; therefore, the greatest breadth of the braincase equals or exceeds the mastoid breadth, whereas the reverse is ordinarily true of rixosa.

Geographic variation.—In the Old World four subspecies are currently recognized (see Allen, 1933:316) and the same number is here recognized in North America. Length of the tail, length of head and body and hind foot, breadth of the rostral part of the skull in relation to its length, and position on the side of the head of the line of demarcation between the dark color of the upper parts and the white underparts, are the features in which geographic variation has been detected. The general impression is that the amount of geographic variation is much less than in Mustela frenata and only slightly less than in Mustela erminea of the same geographic area.

Nomenclature.—It is exceptional for a species which occurs in both the Old- and New-World to take its specific name from New World material, especially if the name was proposed as recently as 1896; most circumboreal species take their names from descriptions of European specimens. Although the least weasel, Mustela rixosa (Bangs) 1896, seems now to be an exception, it may yet turn out that the first available name was based on European material. Zimmermann (1943) shows that the least weasel actually was named on the basis of European material long before 1896 and concludes that the name Putorius minutus Pomel, 1853, based on a specimen from France, is the first available name.

Because Putorius nowadays is relegated to subgeneric rank under the generic name Mustela, we have for consideration the name-combination Mustela minuta (Pomel). Unfortunately for Zimmermann's conclusion, Mustela minuta Pomel is not available because it is preoccupied by Mustela minuta Gervais [= Palaeogale minuta (Gervais), 1848-1852—see Simpson, 1946: 2, 12], a name applied to another species of small mustelid from the Oligocene or lower Miocene deposits of Europe.

Some other early names thought by Zimmermann (1943:290) to have been based on the dwarf weasel of Europe are judged to be nomina nuda and therefore are to be ignored.

The name Mustela minor Nilsson 1820 was thought by Miller (1912:402) to be a renaming, and hence a synonym, of Mustela nivalis Linnaeus. If that is the case the name does not apply to the dwarf weasel. If the name Mustela minor Nilsson was instead based on the dwarf weasel, the name might still be unavailable, depending on rulings on secondary homonyms, because the name might be preoccupied by [Lutra] minor Erxleben 1777 which is a synonym of [Mustela] lutreola Linnaeus 1766. Two names seemingly available for weasels, and in use for them today, which might replace rixosa as the name of the species, are, first, Mustela boccamela Bechstein, 1801, of Sardinia [= Mustela nivalis boccamela of Miller, 1912, 405] and second, Putorius numidicus Pucheran, 1855, of Morocco and Algeria [= Mustela numidica of Allen, G. M., 1939, 183]. As they stand in the current literature, Mustela numidica is a species distinct from the dwarf weasel and the other name, Mustela nivalis boccamela, is an insular subspecies of the mouse weasel. Zimmermann (1943:292), however, implies that M. numidica may belong to the dwarf weasel group when he says "Ob auch iberica Barr.-Ham. als Unterart zu minuta Pom. zu stellen ist, soll hier nicht untersucht werden, ebensowenig die von Cabrera vermutete Zugehörigkeit der grossen nordafrikanischen M. numidica Puch. zur 'iberica-Gruppe'." The answer to this problem requires a taxonomic, rather than a nomenclatural, decision. Whether either M. numidica or M. boccamela are conspecific with the dwarf weasel I cannot at this time ascertain for want of adequate specimens. Because these two names, M. boccamela, and M. numidica, are assigned to kinds of weasels which are currently regarded as specifically distinct from the dwarf weasel, and because all the other names which certainly have been assigned to Old World populations of the dwarf weasel before 1896, so far as I know, are nomina nuda or are preoccupied, the next available name, Mustela rixosa (Bangs, 1896), is here employed.

Remarks.—This species may have a wider geographic range in northeastern North America than is now known. Strong (1930:7) writes that the Naskapi Indians of the interior country of Labrador between Hamilton Inlet and Ungava Bay "have only one name for weasel, mé-tah-kwut, but they say there are three kinds in their territory, a large, an intermediate, and a very small weasel. The latter suggests the least weasel . . . which has not been recorded from northern Labrador."

In the northern part of the range of the species, the winter pelage is white and the summer pelage is brown. In the southern part of the range, that is in the range of the subspecies allegheniensis, the winter pelage is either brown or white and the time of the molt into winter pelage is irregular; each of eleven individuals from Pennsylvania, Michigan and Ohio, taken in December, January, February and March is mostly white but retains some considerable part of the brown pelage of the previous coat on top of the head and usually also along the midline of the entire dorsum. These eleven animals include individuals of each sex. Of each sex, some are adults and some are subadults. Therefore, the delayed or incomplete fall molt, at present, cannot be correlated with either sex or with any particular age. No wild-taken specimens of M. erminea or of M. frenata of the same region show this delayed or incomplete molt.

Possibly this delay or incompleteness of molt is the result of the same cause that lies behind the birth of some M. rixosa in midwinter. As listed below, several litters of young have been found in midwinter. In fact it appears that in the United States, young may be born in every month of the year although, according to existing information, more litters are produced in spring and in winter than in summer and autumn. Many juveniles and young of allegheniensis examined in study collections clearly were born in spring but about as many seem to have been born in midwinter as at any other time (in the light of present knowledge) and this is in contrast to what we know of the two other species of American weasels since their young, so far as known, are born in spring.

One instance is worthy of detailed comment. An adult female, no. 783 Ohio State Museum, taken on January 31, 1931, at Vinton, Meigs County, Ohio, bears the following notation on the attached label "nest plowed out of ground. Very small young escaped—marked like parent. ♀ was nursing." The enlarged mammae on the dried skin substantiate the statement that the female was nursing young. She has a brown mask continuous from one ear through the eye, across the forehead and through the other eye to the opposite ear. On each side of the body a stripe of brown 5 to 10 mm. wide extends from the upper part of the foreleg back to the thigh and base of the tail, uniting there with its opposite and covering the tail. There are a few spots of brown on the shoulders, and rump and one on the middle of the back. Otherwise the specimen is white. One implication of the statement on the label that the young which escaped were marked like the parent (presumably this female parent) is that this female is a partial albino. I am more inclined, however, to the view that there was an unseasonable activity of the particular glands of internal secretion the hormones of which promote embryonic growth and that these glands, or others controlled by them, were in some way responsible for an abnormal progress of molt, or for a reversal of molt in that one molt began before the previous molt had been completed.

Excepting this one specimen, no. 783 from Vinton, Ohio, all of those in transitional pelage indicate that the direction of the molt pattern is the same as in M. frenata and M. erminea. That is to say, the autumnal molt begins on the midventral line and the molt in spring begins on the mid-dorsal line. Furthermore, the normal progress of each molt appears to follow the same pattern that has been described above for Mustela frenata.

A possible explanation of unseasonal molt in the southeastern area of occurrence of the species Mustela rixosa, and a possible explanation of the abnormal molt of the female from Vinton, Ohio, is that the species has only relatively recently invaded the area, and has had insufficient time to adjust the physiology of its molting mechanism to the longer periods of daylight that obtain later in autumn and earlier in spring than farther north. In the other two species of American weasels, the change in length of periods of light, it will be recalled, is known to indirectly control both molt and some changes in the sexual cycle. Wright (1942B:109) has shown that molt in spring precedes by one or two months the birth of young in M. frenata, that the two phenomena are correlated in a way that is statistically significant, and recognizes that progressively longer periods of daylight may be the causal stimulus. The suggestion made above that M. rixosa does not live in New England or in the Rocky Mountains of the western United States because each of the two areas already is inhabited by weasels of almost equally small size, is in line with the idea that rixosa is a recent immigrant to America, or more precisely that rixosa arrived later than erminea.

Natural History.—Habitat and Numbers.—Soper (1946:136) recounts that near the junction of the Antler and Souris rivers, Manitoba, this species occurs "both in the river valleys and on the upper prairies," and later (1948:55), with reference to the Grand Prairie of the Peace River region of Alberta, writes that the least weasel "inhabits both parklands and mixed wood forest environments."

At most times, wherever found, the least weasel is regarded as rare. Not only mammalogists regard it as rare and as a desirable catch, but Indians likewise value it, probably because of its rarity. For example, Osgood (1901:69-70), who caught a female least weasel at Tyonek, Alaska, writes that: "The natives regard the capture of one of these rare animals as a piece of great good fortune. One old Indian who frequently visited our cabin told us that his brother who had caught one when a small boy had in consequence become a 'big chief'; and he assured me that since I had caught one I must surely be destined to become a man of great wealth and power."

Swenk's (1926:313-330) account of the species in Clay County, Nebraska, shows, however, that the animal was far more abundant in 1916 and 1917 than subsequently and inferentially than it was before 1916. Clearest proof of multiannual fluctuation is provided by P. O. Fryklund's (Swanson and Fryklund, 1935:120-126) receipt of weasels from Roseau County, Minnesota. From 1895 to 1932 he had approximately equal opportunity to receive least weasels each year. Those which came to his attention were distributed by years as follows: 1895-1927, 7 individuals in all; winter of 1927-28, 3 individuals; winter of 1928-29, 59 individuals; 1929-1930, 84 individuals; 1930-1935, 3 individuals. "These records indicate a very definite increase in the abundance of least weasels in the Roseau region [in] the two years from the autumn of 1928 to the spring of 1930. Mr. Fryklund has handled 166 least weasels in his 40 years in Roseau County, and of these, 143 were taken in the two years mentioned."

The maximum home range of the least weasel is two acres and a weasel seldom travels farther than ten rods from its burrow according to Polderboer (1942:146) who, in the period December 20, 1939, to January 2, 1940, studied four least weasels and one long-tailed weasel on a 144 acre farm in Butler County, Iowa.

Behavior

Of the voice, Llewellyn (1942:441) records that his captive specimen taken in Virginia uttered a shrill shriek when seizing prey or when teased. When excessively annoyed the weasel also emitted musk.

The sense of smell is used in hunting as was witnessed by George L. Fordyce; he observed a least weasel following the scent of a Peromyscus and saw the least weasel overtake and kill the mouse (Seton, 1929 (2):637).

At a nest in a clover stack, in Manitoba, Criddle (1947:69), on December 27, 1946, found the least weasel "to have been rather remiss in its sanitary habits as its pile of dung was almost, or quite, touching the nest and only just to the side of its entrance." There were 117 voids.

Enemies

The great-horned owl, barn owl and long-tailed weasel are to be counted as enemies since Nelson (1934:252) found the fur, skull and other fragments of the skeleton of a least weasel in one of 26 pellets of the great-horned owl in Wisconsin; Handley (1949:431) found the skull and other skeletal remains of a least weasel in one of 22 pellets of the barn owl in Virginia; and Polderboer, Kuhn and Hendrickson (1941), in Iowa, found the remains of a least weasel in the den and scats of a Mustela frenata. A domestic cat in Michigan killed a least weasel (Dearborn, 1932B:277).

Food

Mice are killed by the least weasel biting into the back of the head and neck according to Allen (1940:460) who reported upon the growth of five young, from Michigan, that he had in captivity. He further states that a weasel was able to kill a mouse in 30 seconds. One large Microtus introduced into the cage slept with a weasel for several days and ate parts of the mice that the weasel killed but then the weasel killed this mouse! Llewellyn (1942:440-441), in writing of a captive from Virginia, says: "When a live mouse was placed in the cage, the weasel sprang upon it almost instantly. Grasping the mouse by the back of the head, the weasel bit its victim through the skull several times in rapid succession and held on with its sharp teeth. The sound of the teeth piercing the bone was distinctly audible at a distance of several feet. During this interval the weasel hugged the mouse closely with its fore legs and pressed it firmly to its belly through a kicking motion of the hind legs. The hold on the back of the head was not relinquished until the mouse was dead. The killing took only a few seconds. Upon releasing the mouse the weasel usually came to the front of the cage and inspected the observer for an interval of several seconds after which it returned to its prey and began its meal at once. Sometimes the blood would be licked from the wound in the back of the head or perhaps an ear would be chewed a bit and the blood licked off, but never did the weasel 'cut the throat' of its prey and 'suck the blood.'

"The weasel ate the head and brain first, beginning at the back of the head and working forward. Just before reaching the nose the process was reversed and eating then proceeded from the base of the skull toward the tail of the mouse. The tip of the nose, maxilla with teeth, and the tail seemed to be the parts least preferred; they were not eaten when an abundance of food was present. At no time did the weasel place its front feet on the mouse in an attempt to hold it. A second or third mouse was killed immediately upon being placed in the cage even though the first one had not been consumed. The weasel, however, usually returned to the partially eaten mouse and finished it before starting on a new one. Upon completing a meal, especially if the meal had been particularly bloody, the weasel rubbed its chin on the bottom of the cage, scooting along and appearing more snakelike than normal. Whenever I attempted to remove a mouse, or partially eaten one, from the cage, the weasel hung to the mouse tenaciously, and often allowed itself to be lifted up in this manner.

"In the six days that the weasel was kept in captivity it was fed 10 house mice having a total weight of 118 grams. As no food was given on one day, the amount of food eaten is probably slightly below the actual capacity of the animal. Since the weasel weighed only about 32 grams, the average amount of food eaten a day was slightly in excess of one-half the weight of the animal."

Polderboer (1942:146-147) found in three dens, in Iowa, bits of Reithrodontomys (harvest mice) and Peromyscus maniculatus (deer mouse), and in the digestive tract of one least weasel there was a bone fragment and a few hairs of a deer mouse. In the account, given beyond, of a nest, Criddle (1947:69) records the Pennsylvania meadow mouse (Microtus pennsylvanicus drummondi) and the Gapper red-backed vole (Clethrionomys gapperi) as prey at Treesbank, Manitoba. The same author, concerning the same place, earlier (1926:199-200) wrote that in 1922 the meadow mouse, Microtus minor, "went into winter quarters in great numbers and its homes were well stocked with provisions . . . all went well until the middle of February, 1923. Then, within a few days, each was taken possession of by a least weasel (Mustela rixosa) and the inhabitants were quickly destroyed. One dwelling was occupied by one of these weasels for about two weeks during which time I observed that it had dragged several mice over the snow to its temporary home. This residence was examined in April, and in it were discovered six dead Microtus minor, one Evotomys, the head of another, and at least six or eight remnants of small rodents including Microtus drummondi, these last remains being chiefly indicated by the hair-lined nest of the weasel.

"The homes of 27 other vole communities examined at this time were all found to have been entered by weasels, the inhabitants having been killed and partly eaten. Moreover, the weasels had made the homes temporary centers from which they raided other rodent habitations in the vicinity. Thus from being an abundant animal this vole was reduced to insignificance in the course of a few weeks, while all other kinds of mice had suffered severely from the same enemy."

An instance of predation on Peromyscus, revealing some of the methods of capturing prey, is recounted by Seton (1929 (2):636-637) who quotes a letter to him from George L. Fordyce, of Youngstown, Ohio, as follows: "While out in the field this morning (Dec. 26), walking along the bank of a ravine at the edge of our golf course, I saw a Field-mouse run out of the bushes into the rough grass that is just outside of the fair-green of the course. In another instant, what I thought at first to be a white Mouse came out at the same place. The Mouse ran into a wheel track, and disappeared under the grass, coming out about 6 feet from where it went in. The white animal followed through the same course, and when it came out, I saw that it was a small Weasel, very little larger than the Mouse, and that it was following the trail of the Mouse by scent.

"For a time the Mouse ran in circles, and zigzagged about, often . . . within 4 or 5 feet of the Weasel; but the latter seemed so intent on the trail, that it did not notice the Mouse to one side. After a time the latter started toward the open golf course; and when the Weasel reached the point where the trail was straight, it sighted the prey, made a sudden dash forward, and, although 25 feet behind, overtook the Mouse while it was going 3 or 4 feet.

"For a few seconds, they seemed to fight, until the Weasel got the Mouse by the throat, and started for the bushes, dragging the body. When it came to within about three feet of me, I moved a little to see what it would do. It dropped its victim, and ran into the ravine. The Mouse had a drop of bright red blood in the center of its white throat. I waited near by for 15 or 20 minutes, thinking the Weasel might come back, but it did not show up again; even an hour later, the Mouse had not been disturbed."

There are two suggestions, but no proof that I know of, in the literature that the least weasel eats insects. Abbott (1884:27-32—1st ed., 1884) gives considerable information on the food (some insects included) of the "little weasel" which he describes (op. cit.; 27) as having "a little pointed tail of a uniform brown color." Although this suggests Mustela rixosa, Abbott mentions on the next page (page 28) that a specimen of the smaller weasel measured six and a half inches from the tip of the snout to the base of the tail and that the tail itself measured two and a fourth inches to the tip of the last caudal vertebra. These measurements indicate that Mustela erminea was involved. Because of the uncertainty as to the species of Mustela involved, Abbott's interesting data on food, nest and behavior are not recorded in the present work. Seton (1929 (2):636) says that of several least weasels brought to D. Nicholson at Morden, Manitoba, most of them decayed so quickly that they could not be saved as specimens. To Seton this indicated that insects were an important part of the food of the weasels.

In summary: Least weasels are known to eat harvest mice, deer mice, meadow mice and red-backed mice; it is suspected that they eat also insects.

Reproduction

Polderboer (1948:296) has taken six specimens in "northeastern Iowa [in] . . . January and December—all males in winter pelage. None of these males showed signs of sexual activity; in all, the testes were retracted and diminutive in size. . . . A male least weasel in brown pelage was taken November 17, 1945, at Marion, Iowa. This specimen had large testes that had descended into the scrotum. The testes, when removed, were about the size of medium-sized garden peas. Microscopic examination of the testes and the vasa deferentia showed mature sperms to be present. . . ."

On July 1, 1917, in Clay County, Nebraska, a nest with four young was found (Swenk, 1926:321). On July 29, 1939, an adult and five young were plowed out of the ground in Allegan County, Michigan; one of the two young males weighed 40.5 grams two days after capture (Allen, 1940:459-460). On August 12, 1932, ten young with the mother, were found in Roseau County, Minnesota (Swanson and Fryklund, 1935:125). September appears to have been the month of birth of a specimen, no. 8472 in the Carnegie Museum, taken on November 24 in Pittsburgh, Pennsylvania. In October, a young least weasel is recorded from Pennsylvania (Winecoff, 1930:313). Early December was the time of birth of a specimen, approximately 10 weeks old, no. 88077, University of Michigan, taken on February 21 in Allegan County. On December 25, 1927, in Washington County, Pennsylvania, "five full-sized, though young . . . animals were caught under the same pile of corn fodder" (Sutton, 1929:253). The first week of January seems to have been the time of birth of a juvenile, no. 88080, University of Michigan, taken in Livingston County, Michigan, on March 27, 1943, since the specimen is approximately seven weeks old. On January 15, 1929, in Washington County, Pennsylvania, four young with the eyes yet unopened were obtained from a nest (Sutton, 1929:254). On January 25, 1928, young, the eyes of which may not yet have been open, were taken from a den in Washington County, Pennsylvania, by Winecoff (1930:313), who records other young having been taken in the same month as well as in February. On March 10, a female from North Portal, Saskatchewan, gave birth to four young (Dunk, 1946:392). On April 18, 1916, four young, half grown, were taken in Nebraska (Swenk, 1926:317). On April 2, 1929, three young were found in Roseau County, Minnesota, according to Swanson and Fryklund (1935:125) who remark that: "The Pennsylvania and Minnesota records show that least weasels may be born any time from July to early February in the northern states." Now, with all of the above records available, it turns out that November, May and June are the only months in which young least weasels have not been reported. Of course some of the young, for which the ages were not specified, were born in preceding months. Even so, the data now available suggests that, in the United States, young least weasels may be born in every month of the year. The number per litter is 3, 4, 4, 4, 5, 5, and 10, yielding an average of 5.

The rate of growth of the young has not been studied enough to allow of judging if it differs significantly from that of other species of the genus. Allen (1940:459-460), however, tells us that of the three young females and two young males captured on July 29, 1939, in Allegan County, Michigan, one male that was killed on July 31, 1939, weighed 40.5 grams. The male remaining alive increased from 46 grams (August 5) to 62.5 grams on September 20, having eaten 63 mice while in captivity. The females in the period of August 5 to September 4 increased in weight as follows: 41 up to 49 grams; 44 to 50 grams; and 47 to 58 grams, having eaten, by September 26, 60, 64 and 65 mice.

Concerning a nest in which young were found, Sutton (1929:254) writes that on January 15, 1929, near Burgettstown, Washington County, Pennsylvania, an animal was seen to enter a small hole in a creek bank. After the observer dug in a distance of approximately six inches an adult, female least weasel was seen and obtained. Back of the animal, the hole, which turned sharply downward, was full of water. The weasel first seen was a female nursing young. A chamber, to the side of the hole, filled with dead grass, comprised a nest containing four young with the eyes yet unopened. Several nests occupied by adult least weasels or by least weasels that were old enough to shift for themselves have been found. Polderboer (1942:145-147) in the winter of 1939-40, on a 144 acre farm in Butler County, Iowa, found four least weasels living, singly, in burrows dug by moles and pocket gophers. The nests therein made by mice were used by the least weasels. Winecoff (1930:312-313) mentions one den in Pennsylvania that contained the remains of only mice, "and not a hint of a feather." Above, in the account of food of the least weasel, Criddle's (1926:199-200) account of the havoc wrought by least weasels among the meadow mice (Microtus ochrogaster minor) has been given. In this account he mentions the fur-lined nests of the weasels that had appropriated the homes of the Microtus. Criddle's (1947:69) later account of a nest at Treesbank, Manitoba, is as follows: "A Nest of the Least Weasel.—When a least weasel finds its way into a locality that has a large number of mice in it, it selects for its home one of their nests that has been made in a well concealed place. This it immediately starts to improve by lining it with hair plucked from its victims before eating them; and as long as sufficient numbers of mice remain in the district the weasel continues adding their hair to the nest, so that the thickness of its walls give one a good idea of the length of time it has been in use. The nest is not only used for sleeping in, as most of the food is consumed in it. Frozen mice are taken in to be thawed out and the weasel carries those it has recently killed in to prevent them getting frozen, or perhaps to have them warm for its next meal.

"On January 27, 1946, my son Percy called my attention to a nest that he had just uncovered in a clover stack that we were using. This nest had originally been made by a Drummond's vole, Microtus pennsylvanicus drummondii, and taken from it by the least weasel, Mustela rixosa, the tracks of which had been noticed about the stack yard since the first snow in early November.

"The nest had evidently been in use for at least three months and the continual additions made to its walls had been so great that they were nearly an inch thick of hair matted together so closely that it appeared to be felt. The hair alone weighed nearly 22 gm., so that with this for protection the weasel must have been warm and comfortable through the severest winter weather.

Fig. 28. Map showing occurrences and probable geographic ranges of the subspecies of Mustela rixosa in North America.

"In the nest were two red-backed mice, Clethrionomys gapperi, one of which had the base of its skull eaten out. No hair had been removed from either of them, but a Microtus lying in a side tunnel some feet away had the long hair plucked from its back and sides. In and close about the nest were found forty-three front parts of mice skulls which had evidently been discarded because of the sharp teeth in the maxillaries. Seven full stomachs and eleven hind feet of adult Microtus with parts of leg bones were disclosed in, or under, the weasel's bed and a few small bits of skin with hair attached were scattered among the plucked hair of the nest.

"This weasel seems to have been rather remiss in its sanitary habits as its pile of dung was almost, or quite, touching the nest and only just to the side of its entrance. It was composed of 117 voids all of which contained much hair and broken bone.

"Six other mouse nests found in the same stack, or others adjoining it, had been thinly lined with hair. One of these had two mice in it, a red-backed with its brain eaten out and a Microtus with some hair plucked from its neck. Another nest contained the front part of a skull with teeth and the hind feet and tail of a red-back. Besides the mice found in the nests seven others were discovered tucked away in side tunnels. One of these mice had most of the hair plucked from its back. Whether all these mice and nests belonged to the same weasel or not I am unable to say, but it is usual for them to have several nests in the area surrounding the one that is used as their headquarters or home."

Mustela rixosa eskimo (Stone)

Least Weasel

Plates 14 and 15

Putorius rixosus eskimo Stone, Proc. Acad. Nat. Sci. Philadelphia, 1900:44, March 24, 1900.

Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877 (part).

Putorius rixosus, Bangs, Proc. Biol. Soc. Washington, 10:21, February 25, 1896 (part); Merriam, N. Amer. Fauna, 11:14, June 30, 1896 (part).

Mustela rixosa eskimo, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Swenk, Journ. Mamm., 7:327, November 23, 1926; Hall, Univ. California Publ. Zoöl., 30:421, March 19, 1929.

Type.—Female, age in question, no. 848 in Acad. Nat. Sci. Philadelphia; Point Barrow, Alaska; July 25, 1898; obtained by E. A. McIlhenny. Type not seen by me.

Range.—Alaska and Yukon Territory. See figure 28 on page 180.

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Characters for ready recognition.—Differs from M. r. pygmaea of eastern Asia in longer tail, averaging 11 rather than 16 per cent of length of head and body, and in study skins reaching only to heel instead of to point between heel and toes; from M. r. rixosa in shorter tail averaging 16 rather than 19 per cent of length of head and body and not extending beyond outstretched hind feet in study skins; white of underparts extending dorsally as a reëntrant angle from upper lip to behind eye, rather than delimited dorsally by a boundary between white and brown color that extends straight across cheeks from upper lip to side of body well below eye and ear; breadth of rostrum measured across lacrimal processes more, instead of less, than 85.5 per cent of orbitonasal length; from M. erminea of same region by basilar length of skull less than 32; tail less than 50 and lacking black pencil.

Description.—Size.—Male: The original describer lists measurements of topotypes as follows: Total length, 204, 230; length of tail, 28, 31; length of hind foot, 20, 22. Allowing 5 per cent for shrinkage, the hind feet of 5 topotypes yield an average measurement of 23 for the hind foot.

Female: Measurements of two topotypes are: Total length, 184, 180; length of tail, 25, 25; length of hind foot, 24, 18. In four other topotypes the hind feet, allowing 5 per cent for shrinkage, yield an average of 21.

Color.—Winter pelage all white, rarely with few white hairs in tip of tail but no black pencil; summer pelage with upper parts about Raw Umber and tone 3 of Chocolate pl. 343 of Oberthür and Dauthenay; underparts white, extending over upper lip, insides of limbs and over all four feet. Line of demarcation between underparts and upper parts extends from upper lip posterodorsally to behind eye down to base of ear, up behind ear for a third or more of its height, and back along side of body. Tail unicolor all around and same color as upper parts. Least width of color of underparts averaging 83 per cent of greatest width of color of upper parts.

Skull.—Based on topotypes; see measurements and plates 14 and 15; weight, 0.82 (0.74-0.93) grams in males, and 0.80 and 0.84 in two females; basilar length, 29.5 (27.6-30.1) in males and 27.8 (27.1-28.8) in females; otherwise as described in M. e. richardsonii.

Remarks.—Among the earliest specimens preserved was one by Edward W. Nelson in the course of his explorations of the Upper Yukon, and one in 1874 by L. T. Turner from St. Michaels, Alaska. Bangs, in 1896 (p. 22) mentioned the occurrence of the species in Alaska, but it was not until 1900 (p. 44) that Stone named the subspecies, and then principally on the basis of specimens obtained two years before by E. A. McIlhenny.

The large size, broad skull, light color and short tail are the distinguishing subspecific characters of the race eskimo, and the three characters first mentioned are distinguishing features also of the subspecies of Mustela erminea, namely arctica, which inhabits the same region. Possibly eskimo also will be found on Banks Island and the other Arctic islands between Alaska and Greenland, as is M. e. arctica; at the present time no specimens of Mustela rixosa are known from these islands although some race of rixosa would be expected to occur there.

Animals from southern Alaska average slightly smaller than those from northern Alaska, and this decrease in size toward the south probably represents intergradation with M. r. rixosa. Further evidence of intergradation is furnished by the short tail of the specimen from 15 miles east of Atlin; in other particulars this specimen agrees with the subspecies rixosa to which it is here referred. Nevertheless, the short tail, and color pattern, namely reëntrant angle of white behind the eye, is to be seen in all Alaskan specimens examined in the brown pelage, even in no. 107591, from Tyonek on Cook Inlet, which Osgood (1901:69) and Swenk (1926:323) thought might not differ from the subspecies M. r. rixosa.

Each of four male topotypes, hardly subadult in age, probably of a single litter, is much larger than any other specimen seen from Point Barrow. The basilar length, for example, is 31.9 as against 29.5, and the weight of the skull (with lower jaws) is as much as 1.5 grams, as against 0.93 in the heaviest of the other males. Initial examination of materials from Point Barrow raised the suspicion that two distinct species were represented—rixosa and a larger one possibly allied to M. nivalis of the Old World. Nevertheless, further study almost completely allayed the suspicion because the only difference discernible is one of size, and it is supposed that additional specimens will bridge the gap in size and show that M. r. eskimo at Point Barrow averages larger than the adult specimens now available indicate. The four large males of subadult age are nos. 42814-42816 and 42818 of the American Museum of Natural History.

Of the fourteen adult and subadult skulls examined, two display lesions resulting from infestation of the frontal sinuses by nematode parasites. None of the young skulls show such infestation.

Specimens examined.—Total number, 42 as follows. Arranged alphabetically by Territory and District and unless otherwise indicated in the United States National Museum.

Alaska. Barrow and Point Barrow, 19 (8[2], 7[74], 2[1], 1[50]); Wainwright, 1[57]; Mts. back of Icy Cape, 1[77]; west of Beechey Point, 1[2]; west edge of Colville River Delta, 1[2]; Koyukuk River, 16 mi. above Beetles, 1; upper Yukon, 1; Fort Yukon, 1; Stephens Village, 1; Wales, 1[57]; McDonald Creek, tributary of Salcha Slough, 1; near head of Toklat River, 1; head of Kantishna River, 1; St. Michael, 4 (2[74]); Tyonek [= Tyonek], 1; Bethel, 3; vic. Bristol Bay, 1.

Yukon. La Pierre's House, 1; Klotassin River, tributary of White River, 1.

Mustela rixosa rixosa (Bangs)

Least Weasel

Plates 14 and 15

Putorius rixosus Bangs, Proc. Biol. Soc. Washington, 10:21, pl. 1, fig. 6, pl. 2, fig. 6, pl. 3, fig. 4, February 25, 1896; Merriam, N. Amer. Fauna, 11:14, pl. 2, figs. 7, 7a, June 30, 1896.

Putorius pusillus, Baird, Mamm. N. Amer., p. 159, 1858.

Putorius (Gale) vulgaris, Coues, Fur-bearing animals, p. 102, 1877.

Mustela rixosa, Thomas, Proc. Zoöl. Soc. London, p. 168, March, 1911.

Mustela rixosa rixosa, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912; Swenk, Journ. Mamm., 7:327, November 23, 1926.

Type.—Female, adult, skin and skull; no. 642 Bangs Coll. in Mus. Comp. Zoöl.; Osler, Saskatchewan; July 15, 1893; obtained by W. C. Colt; original no. 79 according to describer.

The skull lacks the basioccipital, basisphenoid, and left zygomatic arch. The "crowns" of the lower canines are missing; otherwise the teeth are present and entire. The skin is fairly well made, with soles of hind feet up, in good condition and in summer pelage.

Range.—From northern British Columbia and Great Slave Lake south on the west side of the Rocky Mountains to Ootsa Lake, British Columbia, and on the east side of the Rocky Mountains, south to central Montana, North Dakota and Minnesota; eastward in Canada, entirely north of St. Lawrence River, to Atlantic Ocean. See figure 28 on page 180.

Characters for ready recognition.—Differs from M. r. eskimo in longer tail averaging 19 rather than 16 per cent of length of head and body and extending beyond outstretched hind feet in study skins, rather than to a point short of tips of toes; boundary between brown upper parts and white underparts extending straight across cheeks from upper lip to side of body well below eye and ear, rather than with reëntrant angle from upper lip carrying white upward to point behind eye, and with breadth of rostrum less, instead of more, than 85.5 per cent of orbitonasal length; from M. r. campestris by smaller size: hind foot less than 25 in males and ordinarily less than 22 in females; in males total length less than 216 and tail averaging less than 34, and in females total length averaging less than 182 and tail averaging less than 29; color said to average darker; from M. r. allegheniensis by three average differences, namely lighter color, longer tympanic bullae and larger size of males; from M. frenata and M. erminea of same region by basilar length of skull less than 32; tail less than 50, and lacking black pencil.

Description.—Size.—Male: Six adults and subadults from Shaunavon, Saskatchewan, yield average and extreme measurements as follows: Total length, 202 (188-208); length of tail, 32.5 (31.5-34.0); length of hind foot, 22.8 (21-24).

Female: One adult and 3 subadults from the same area yield average and extreme measurements as follows: Total length, 172 (162-190.5); length of tail, 27.4 (24-34); length of hind foot, 19.6 (17.5-22).

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Color.—Winter pelage all white, rarely brown; as described in M. r. eskimo except that line of demarcation on side of head between upper parts and underparts passes almost straight back without the dorsally directed reëntrant area of white behind the eye and ear; least width of color of underparts averaging 52 per cent of greatest width of color of upper parts.

Skull (Based on those from Shaunavon, Sask.)—See measurements and plates 14 and 15; weight, 0.88 (0.70-0.98) grams in males and 0.55 (0.54-0.56) in females; basilar length, 29.5 (28.4-30.4) in males and 26.1 (24.7-27.0) in females; otherwise as described in M. e. richardsonii.

Remarks.—As early as 1858 (p. 159) Baird recognized an individual of this race from Pembina, Minnesota, as pertaining to a distinct species. Although he used for it the specific name pusillus originally proposed by DeKay for a small weasel from the state of New York, Baird wisely noted that the specimen he described "may be different from the New York species. . . ." After preparing this account, Baird included a second specimen, from Fort Steilacoom, Washington Territory, which he thought might be the same, but the differences that he was careful to point out, in the light of later knowledge, show it to be of the species Mustela erminea. Only a few other naturalists followed Baird in distinguishing the least weasel as a separate species until Bangs in 1896 (p. 21) clearly differentiated it and proposed for it the name Putorius rixosus, which continues in use today and applies to the species.

The accumulation at the National Museum of Canada, through the energy of Dr. R. M. Anderson, of a good series of specimens from Saskatchewan in the general vicinity of the type locality allows for the first time an adequate conception of the amount of secondary sexual variation and individual variation and permits recognition of subspecific characters to differentiate between M. r. rixosa and the subspecies eskimo and campestris. In comparison with the subspecies allegheniensis the basis for segregation is less clear and will remain somewhat in doubt until additional adults of allegheniensis from, say, Pennsylvania, become available with accurate external measurements taken in the flesh and especially with complete skulls.

Intergradation with the subspecies eskimo is suggested by the short tail of the specimen from fifteen miles east of Atlin, British Columbia; in other particulars that specimen, a skin-alone, agrees with the subspecies rixosa. Intergradation with campestris is indicated by increased size of some specimens from North Dakota, and is suggested with allegheniensis by the color of specimens from Wisconsin and Illinois. Three specimens from Winona County, in southeastern Minnesota, unfortunately are skulls-alone without external measurements. Also, two of these skulls are of young animals. The one adult, unsexed, is from Crystal Springs. Selected cranial measurements are: basilar length, 28.5; length of tympanic bulla, 10.9. These measurements accord with those of males of the subspecies rixosa to which the specimens from Winona County, therefore, are here assigned. The possibilities have not been excluded, however, that the adult is an unusually large female of the subspecies campestris or a male of allegheniensis that has tympanic bullae longer than average for that subspecies.

Some hesitation is felt in assigning the specimens, 8 in all, from eastern Canada to the subspecies rixosa. The skin-alone from Eagle River and the skin, with part of the skull, from St. Michael Bay, are in transitional pelage and are of no help in appraising subspecific characters. The one adult specimen which does have a complete skull is from an island south of the Comb Hills. This animal in all respects agrees with selected individuals of M. r. rixosa from Saskatchewan, but each of the five other skins in summer pelage has spots of dark brown color on the breast. Only about one specimen in three of rixosa from Saskatchewan is similarly marked. Furthermore, on some of the specimens from eastern Canada the spots are larger than on any of the animals from farther west. The greater frequency of brown spots on the breast, the larger average size of these spots, and the darker average coloration of the upper parts are suggestive of geographic variation, the existence of which has to be proved by additional and more complete specimens from eastern Canada. For the time being, specimens from there are tentatively assigned to the race rixosa.

Of 56 subadult and adult skulls only 3 (1 North Dakota; 1 Calgary, Alberta; and 1 Island S Comb Hills, Queb.) display lesions resulting from infestation of the frontal sinuses by nematode parasites. None of the young skulls shows such infestation.

Specimens examined.—Total number, 87 as follows. Arranged alphabetically by provinces and states and within each from north to south. Unless otherwise indicated, specimens are in the United States National Museum.

Alberta. Miette River, 1[77]; 5 mi. NW Camrose, 1[77]; Camrose, 2 (1[77], 1[31]); "near Camrose," 2[77]; Forks Blindman and Red Deer rivers, 1[60]; Innisfail, 1[86]; Veteran, 1[93]; Diddsbury [= Didsbury], 1; Calgary, 2 (1[93], 1[2]); Shepard, 1[86].

British Columbia. Clarks Ranch, Halfway River, Peace River Dist., 1[85]; 15 mi. E Atlin, 1[8]; Wistaria, P. O., 3 (2[77], 1[85]); Ootsa Lake, 1[85].

Labrador. Davis Inlet, 1[60]; 30 mi. upriver and 20 mi. toward Groswater Mts., Eagle River, 1; St. Michael Bay, 1.

Mackenzie. Old Fort Reliance, 1[2]; Fort Resolution, 2; Fort Smith, 1.

Manitoba. Gypsumville, 1[86]; Lake St. Martin Reserve, 1[86].

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Minnesota. Roseau County: Cedarbend, 2[14]; Grimstad, 1[14]; America, 2 (1[14], 1[74]); Malung, 1[74]; Norland, 1[41]; Falun, 3 (1[14], 1[74], 1[41]); Palmville, 1[41]; Spruce, 1[74]; Stokes, 1[74]. No locality more definite than Marshall County, 1[14]. Clay County: Moorhead, 1[36]. Winona County: "near" Whitman, 1[34]; Altura, 1[98]; Crystal Springs, 1[98].

Montana. Sun River Valley, 1; Wibaux in Wibaux County, 1.

North Dakota. Walsh County: Grafton, 15 (3[60], 1[93], 5[2], 2[14], 1[74], 1[1], 1[76]). McHenry County: 4 and 4-1/2 mi. N Upham, 2. Wells County: 1[36]. Morton County: Mandan, 1[60].

Ontario. Algoma Dist.: Tatnall, near Oba, 1[86]. Moose Factory, 1[75].

Quebec. Island S of Comb Hills, James Bay, 1[9]. Saguenay County: Natashkwan, 1.

Saskatchewan. Osler, 1[75]; "near Regina," 1[77]; Dollard, 2[31]; Shaunavon (and "near" and 1 mi. NE), 9[77]; Klintowel P. O. (about 15 mi. N of Eastend), 1[77]; Eastend and "near" Eastend, 2[77].

Mustela rixosa allegheniensis (Rhoads)

Least Weasel

Plates 14, 15 and 41

Putorius allegheniensis Rhoads, Proc. Acad. Nat. Sci. Philadelphia, 1900:751, March 25, 1901.

Putorius rixosus allegheniensis, Cory, Mamm. Illinois and Wisconsin, p. 378, 1912.

Mustela allegheniensis, Miller, U. S. Nat. Mus. Bull., 79:96, December 31, 1912.

Mustela rixosa allegheniensis, Swenk, Journ. Mamm., 7:328, November 23, 1926.

Type.—Probably male adult, skin and skull, no. 6195, Acad. Nat. Sci. Philadelphia; near Beallsville, Washington Co., Pa.; about 1885 or 1886; obtained by Robert Hawkins.

Type not seen by me.

Range.—Wisconsin, northern Illinois, northern Indiana, Michigan, Ohio, Pennsylvania east to Dauphin County and south in the mountains to northwestern North Carolina. See figure 28 on page 180.

Characters for ready recognition.—Distinguished from M. r. rixosa by three average differences, namely, darker color, shorter tympanic bullae, and smaller size of males; from M. r. campestris in smaller size: hind foot less than 25 in males and less than 22 in females; in males total length less than 216 and tail averaging less than 34, color averaging darker; from M. frenata and M. erminea of same region by basilar length less than 31, tail less than 45, and lacking black pencil.

Description.—Size.—Male: An adult or subadult from Fair Oaks, Pa., a subadult from Finleyville, Pa., and an adult from Huttonsville, W. Va., measure, respectively as follows: Total length, 206, 194, 191 (average 197); length of tail, 37, 32, 28 (32); length of hind foot, 23 in each. An adult from Roanoke, Indiana, weighs 40.6 grams.

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Female: Two young from Leasuresville, Pa., and Middle Paxton Twp., Pa., measure, respectively, as follows: Total length, 188, 172; length of tail, 33, 30; length of hind foot, 20.5, 21. An adult from Monroeville, Ohio, weighs 40.5 grams and a young individual from Middle Paxton Twp., Pa., 39.3 grams, and a subadult from Swan Creek Exp. Station, Allegan Co., Mich., weighs 49 grams.

Color.—Winter pelage either all white, or brown as in summer; upper parts about Raw Umber, or tone 2 of Carbo Brown of pl. 342 of Oberthür and Dauthenay. Underparts white at least on thoracic region; approximately three-fourths of specimens with brown rictal spot at angle of mouth or with this area covered by brown upper parts which extend down on each side and meet on the underparts in about one specimen out of three; upper lips and hind feet ordinarily brown; toes of forefeet ordinarily white (see under remarks for details of color pattern). Least width of color of underparts in the specimens in which the dark color of the upper parts does not encircle the body averages 60 per cent of greatest width of color of upper parts, or including all specimens the percentage is 42.

Skull (based on specimens from Pa. listed in table of cranial measurements, which see and plates 14 and 15).—Basilar length 29.7 and 28.6 in male and 28.0 in female; weights unavailable; otherwise as described in M. e. richardsonii. The length of the tympanic bullae seems to be actually less, and less in relation to the basilar length, than in other American subspecies of M. rixosa.

Remarks.—Robert Kennicott's mention in 1859 (p. 245) of what seems to be this subspecies is the earliest reference to it that I can identify in the literature. He used the specific name pusillus and it was not until 1900 that Samuel N. Rhoads proposed the name Putorius allegheniensis. Since 1900, several records of occurrence have been published which have made the geographic range of this race better known.

An adequate number of specimens has been gathered only from Ohio and from western Pennsylvania. Many from Ohio are without accurate external measurements taken in the flesh. The majority of the specimens from Pennsylvania owe their preservation to the willingness of local officials, who pay bounties on weasels, to save the skins of Mustela rixosa. These specimens ordinarily comprise the skin with locality but because the feet, external measurements in the flesh, and skulls are unavailable, the material is far from adequate and to give an accurate notion of the usual or average cranial characters of allegheniensis in Pennsylvania, skulls from there are especially desirable.

A smaller percentage of the specimens from Ohio than from Pennsylvania have the brown color of the upper parts meeting on the underparts. Also, more of the specimens from Ohio are lighter colored and this suggests intergradation with the subspecies campestris and rixosa to the westward.

From Pennsylvania 23 animals in brown pelage are available. In 5 there is a rictal spot at the angle of the mouth; in 5 the area is white and in 13 the brown color of the upper parts is continuous over the area in question. Only 2 of 23 have the upper lips white. Eight have the color of the upper parts meeting on the venter thus restricting the white of the underparts to the chin, throat, and pectoral region, and 6 of these have a white area in the inguinal region as well. The toes of the forefeet are white in 3 of 4 animals suitable for examination in this regard and the hind feet are marked with white in 3 of the 8 animals which have the hind feet preserved. Mustela rixosa in Pennsylvania parallels the species Mustela frenata in that in this relatively humid area of the northeastern United States the color of the upper parts is darker and the area of the dark-colored upper parts is increased at the expense of the area of the light-colored underparts. Also Mustela erminea in this same region (range of the subspecies Mustela cicognanii) shows the same tendency to darker color of upper parts and their extension in area at the expense of the area of the light-colored underparts, or was mentioned above.

It is difficult to account for the seeming absence of the species from New England and all that part of Canada and the United States south of the St. Lawrence River and northeastward from Pennsylvania. The size of females of M. erminea cicognanii in that territory is so little more than in rixosa that the latter possibly cannot successfully compete with the erminea stock which may already occupy the ecologic niche to which rixosa is adapted. It will be remembered that in western North America in territory seemingly climatically suitable for rixosa it occurs no farther southward than the line below which M. erminea has become reduced to a size comparable with that of M. rixosa.

Of 41 subadult and adult skulls assigned to this subspecies 24 have obvious lesions in the frontal sinuses evidently resulting from infestation by nematodes. More in detail, none of the specimens from Illinois (3 individuals), Pennsylvania (3 barely subadult), or West Virginia (2) displays lesions. From Wisconsin, Indiana, Virginia and North Carolina there is one specimen each and each specimen displays lesions. From Ohio, 17 of 23 specimens display lesions. From Michigan 3 of 8 specimens display lesions; 2 adults and one subadult have lesions and 5 subadults do not have lesions.

Specimens examined.—Total number, 102 as follows: Arranged alphabetically by states and within each state by counties from north to south. Unless otherwise indicated, specimens are in the United States National Museum.

Indiana. Huntington County: Roanoke, 1. Wells County: Harrison Township, 1[76].

Illinois. Lake County: Deerfield, 3[60]; no locality more definite than county, 1[60]. Cook County: Northfield, 1[60]; La Grange, 1[18].

Michigan. Tuscola County: 8 mi. N Caro, 1[76]. Santilac County: Deckerville, 1[76]. Allegan County: Swan Creek Exp. Station, 1[76]; Swan Creek Farm, 1[76]; T. 2N, R. 14W, 1[76]; Allegan, 1[76]. Livingston County: George Reserve, 1[76]; 1/2 mi. N Unadilla, 1. Oakland County: Rochester, 1[76]. Macomb County: Romeo, 1[76]. Washtenaw County: 5 mi. SW Ann Arbor, 1[76]. Branch County: vic. Coldwater, 1[76].

North Carolina. "near Marshall," 1.

Ohio. Northern part of state, 1[81]. Williams County: Stryker, 1[60]. Lucas County: Monclova, 1[60]. Erie County: Sandusky, 2[76]; marsh near Sandusky, 1[76]; Berlin Heights, 1[76]; no locality more definite than county, 1[2]. Wood County: 10 mi. NE Bowling Green, 1[76]; Bowling Green, 4[76]; 3 mi. E Bowling Green 1[76]; Plain Township, 1[2]; Portage Township, 1[60]. Loraine County: Wellington, 1[81]. Huron County: west of Monroeville, 1[76]. Summit County: Ira, 3[81]. Portage County: Suffield, 1[81]. Hancock County: Vanburen, 1[76]; Findlay, 1[81]; 9 mi. S Findlay, 1[76]; no locality more definite than county, 7 (2[76], 2[81], 3[2]). Mahoning County: Ellsworth, 1. Crawford County: "near Crestline," 1[81]. Delaware County: Sunbury, 1[2]; Lewis Center, 1[81]; no locality more definite than county, 1[81]. Licking County: Johnstown, 1[2]. Fairfield County: Baltimore, 1[81]; Violet Township, 1[81]. Meigs [= Gallia?] County: Vinton, 1[81].

Pennsylvania. Erie County: McKeen Twp. 1. Crawford County: Springboro, 1[1]; Pymatuning Swamp, between Hartstown and Shermansville, Sadsbury Twp., 3[9]. Mercer County: Shenango Twp., 1. Lawrence County: Little Beaver Twp., 1. Butler County: Leasuresville, 1[9]; Clearfield Twp., 1; Valencia, 1[9]. Armstrong County: Ford City, Burrell Twp., 1. Indiana County: Smicksburg, 1; N. Mahoning Twp., 2; White Twp., 1. Allegheny County: South Hills, Pittsburgh, 1[9]; "near Pittsburgh," 1[9]; Fair Oaks, 1[9]. Westmoreland County: Bolivar, 1. Dauphin County: Middle Paxton Twp., 1. Washington County: Finleyville, 1; Rea, 5; Beallsville, 1[1]; Claysville, 1. Green County: Deep Valley, 1; Waynesburg, 1; Jefferson, 1; Cumberland Twp., 1. Fayette County: Acme, 1[9]. Somerset County, 1. Lancaster County, 1.

West Virginia. Randolph County: Huttonsville, 1.

Wisconsin. Sauk County: Sumpter Twp., 1[60]. Dodge County: Beaver Dam, 1[50]. Dane County: Madison, 1; McFarland (= MacFarland), 1.

Mustela rixosa campestris Jackson

Least Weasel

Plates 14 and 15

Mustela campestris Jackson, Proc. Biol. Soc. Washington, 26:124, May 21, 1913.

Putorius pusillus, Aughey, Sketches of the physical geography and geology of Nebraska, p. 119, 1880, Omaha.

Mustela rixosa campestris, Swenk, Journ. Mamm., 7:329, Nov. 23, 1926.

Type.—Female, adult, skin and skull; no. 171490, U. S. Nat. Mus., Biol. Surv. Coll.; Beemer, Cuming County, Nebraska; April 18, 1911; obtained by G. Sharp; x catalogue no. 8440.

[191]

The skull is unbroken. On the left side, C1 and P2 are missing; the other teeth are present and entire. The skin is excellently made and in a good state of preservation.

Range.—South Dakota, Nebraska and Iowa. See figure 28 on page 180.

Characters for ready recognition.—Differs from M. r. rixosa and M. r. allegheniensis in larger size: Hind foot more than 25 in males and ordinarily more than 22 in females; in males total length more than 216 and tail averaging more than 34; color possibly slightly paler than in M. r. rixosa and averaging paler than in M. r. allegheniensis; from M. frenata and M. erminea of the same region by basilar length less than 32; tail less than 50, and lacking black pencil.

Description.—Size.—Male: Four adults from Nebraska yield average and extreme measurements as follows: Total length, 231 (225-237); length of tail, 36 (32-39); length of hind foot, 29 (28-31).

Female: Six adults from Nebraska yield average and extreme measurements as follows: Total length, 192 (184-225); length of tail, 35 (28-40); length of hind foot, 23 (20.5-26).

Color.—Winter pelage ordinarily white; as described in M. r. eskimo except possibly paler and certainly with line of demarcation on side of head between upper parts and underparts passing almost straight back without the dorsally directed reëntrant angles of white behind the eye and ear; least width of color of underparts in four specimens from Nebraska averaging 80 (49-89) per cent of greatest width of color of upper parts, but in a fifth animal in summer pelage the brown color of the upper parts encircles the body.

Skull.—See measurements in table and plate 15; weight 1.1 grams (male from Brown Co., S. D.); basilar length, 30.7 in male from Clay Co., Neb., and 28.8 in female from same county; otherwise as described in M. e. richardsonii.

Remarks.—In his revisionary treatment of the American races of Mustela rixosa, Myron H. Swenk (1926:313) credits Samuel Aughey with recording this animal, M. r. campestris, from Nebraska, as early as 1880, under the name Putorius pusillus. In 1908, Swenk recorded the animal from the same state under the name rixosus and in 1913 the race campestris was formally named by H. H. T. Jackson.

On the testimony of a friend who had previously obtained several specimens for him, Swenk (1926:321) records the least weasel from Oshkosh, Garden County, Nebraska, which is a marginal record of occurrence to the southwest for M. r. campestris.

At an early stage in the study of American weasels the writer examined the specimens from Nebraska saved by Mr. Myron H. Swenk and recorded measurements of them. However, at the time of writing this account the specimens were not available for examination and the account of coloration is accordingly incomplete.

The large size, particularly the large external measurements, comprises the principal distinguishing character of this subspecies of the least weasel.

Of the four adults examined from Iowa and South Dakota one exhibits lesions such as result from infestation of the frontal sinuses by nematodes.

Specimens examined.—Total number, 21 as follows. Arranged alphabetically by states and by counties, from north to south in each state. Unless otherwise indicated, specimens are in the United States National Museum.

Iowa. Howard County: Chester, 1[12]. Palo Alto County: Emmetsburg, 1[65]. Kassuth County: Algona, 1[65]. Clayton County: National, 1. Storey County: Nevada, 1[65]. Wapello County: Ottumwa, 1[65]. Henry County: Mount Pleasant, 1[66].

Nebraska. Holt County: Page, 1[35]. Madison County: Norfolk 1[35]. Cuming County: Beemer, 1. Hamilton County: Chapman, 1[35]. Clay County: Inland to 1 mi. east thereof, 7[35].

South Dakota. Brown County: shore of Sand Lake, S. 15 T. 126N, R. 62W, 1. Day County: Waubay Migratory Waterfowl Refuge, 1. McCook County: Salem, 1[102].

MUSTELA FRENATA Lichtenstein

Long-tailed Weasel

(Synonymy under subspecies)

Type.—Mustela frenata Lichtenstein, Darstellung neuer oder wenig bekannter Säugethiere, pl. 42 and corresponding text unpaged. 1832.

Range.—From southern Canada southward over all of the United States, México, Central America, Venezuela, and the republics of western South America to southern Perú and extreme northern Bolivia. All the life-zones from Alpine Arctic to Tropical are inhabited. In the extremely desert region of southeastern California and western Arizona the species is scarce or possibly absent although recovery of a skull (see under account of M. f. neomexicana) from near the center of this region at Potholes on the Colorado River, and a reported occurrence in the mountains of Baja California, México, indicate that a few individuals of the species live in favorable habitat even in this desert region.

Characters for ready recognition.—Differs from Mustela erminea, in regions where the two species occur together, by tail more than 44 per cent of length of head and body and by postglenoidal length of skull less than 46 per cent of condylobasal length in males and less than 48 per cent in females (see under characters of the species); from Mustela rixosa by presence of black pencil on tail, caudal vertebrae more than a fourth (2/5-3/4) of length of head and body, basilar length of skull more than 34 mm.; from Mustela africana by absence of thenar pad on forefoot, underparts without longitudinal, median, abdominal stripe of same color as upper parts, upper lips narrowly (rather than broadly) edged with color of underparts, longest facial vibrissae extending to or behind posterior margin of ear; presence of p2; more inflated (see pls. 23 and 30) tympanic bullae.

Characters of the species.—Size large: Total length 300 to 550 mm.; tail two-fifths to seven-tenths of length of head and body, with distinct black pencil at end; caudal vertebrae 19 to 23; skull with long precranial portion; postglenoidal length, expressed as a percentage of the condylobasal length, less than 47 in females and ordinarily less than 46 in males; upper parts brown; light-colored underparts, in summer pelage, tinged with buffy or yellowish and continuous from chin to inguinal region; some subspecies (southwestern United States, México, Central America, and Florida) with white or yellowish facial markings which do not occur in any other American species of the genus Mustela.

Geographic variation.—Forty-two subspecies are recognized, and the species is geographically more variable than any of the other 3 American species. Color, color-pattern especially on the head, relative proportions of the tail, hind feet, body including the head, and shape and size of the skull are the principal features in which geographic variation has been noted. The variation in the skull extends to the basicranial region (shape and size of tympanic bullae and related structures), interorbital region and preorbital region.

Natural History.—Habitat and Numbers.—As has already been remarked, the long-tailed weasel is absent from the extreme desert of the southwestern United States and northwestern México. Possibly the absence of water to drink is the limiting factor. In southern Nevada the finding of weasels only in places that were well watered, even though small rodents suitable as food for weasels were even more abundant in the surrounding desert, supports this possibility that the absence of water to drink is the limiting factor. Also at Berkeley, California, in early December of 1927 in the canyon at the head of Dwight Way and in the autumn and winter of 1928 in Strawberry Canyon on the campus of the University of California, I trapped extensively for this species in different habitats and obtained, in all, four individuals no one of which was farther than 10 feet from water. The lesser cruising range of the individual weasel than of, say, the coyote, probably explains why, in an arid region, for example Pahranagat Valley, Nevada, only the meadow mice and their riparian associates are preyed upon by the long-tailed weasel whereas the coyote preys upon these riparian rodents and also upon the kangaroo rats and other rodents which are so abundant in adjoining habitats that are devoid of water.

In areas where water is available every few hundred yards, no particular habitat seems to be avoided in summer providing there is food for the long-tailed weasel. In winter (January and March) there obviously was a choice of habitat, possibly occasioned by more abundant food or more satisfactory shelter, or both, in Centre County, Pennsylvania, where Glover (1943B) found the population density in the chestnut-oak habitat to be one weasel per 6.5 acres in areas of tree cuttings and slash and one weasel per 13.3 acres in the open forest. In the scrub oak-pitch pine forest type the population was one weasel per 26.4 acres in tree cuttings and slash and one weasel per 38.2 acres in the open forest. No weasel was found in an area of 9.6 acres comprising a wood lot, the edge of the forest, abandoned fence rows and an abandoned orchard. The two types of forest in which he did find weasels, 25 in all, comprised 381.6 acres. Glover's (op. cit.) data is the only precise information known to me on actual numbers of long-tailed weasels in a given area of any considerable size.

Fluctuations which I elsewhere (1946:57) have designated as multiannual fluctuations occur in this species but seemingly not in the degree that they do in Mustela erminea. This difference between the two species is to be expected because M. frenata does not range so far northward toward the polar regions as does M. erminea and populations of most kinds of animals in the polar, at least in the arctic, regions are subject to more extreme and more regular fluctuations than are kinds of animals in temperate or tropical regions. Indication of the means by which decrease in the weasel population is brought about is afforded by Osgood's (1935:156) observations around Rutland, Vermont. In the late winter of 1934, tracks indicated that weasels left their usual haunts and hunted cross lots, vainly trying to find food. Testing of the small mammal population in the spring and summer of 1934 showed that it was at low ebb. In the fall of 1934 mice and shrews were abundant again but weasels seemed to be entirely absent. The decrease in the population of weasels lagged behind the decrease in the population of the herbivorous prey as did the subsequent increase; this, of course, is the normal relation of carnivorous species of mammals and their prey, at least in and above the Transition Life-zone.

The average distance away from the central den which four weasels (sex unspecified) traveled in a single night at Ames, Iowa, was 312 feet; the maximum distance was 642 feet. These data were obtained in the winter of 1939 by Polderboer, Kuhn and Hendrickson (1941:115) who studied the tracks in the snow. In Manitoba, Criddle and Criddle (1925:143) noted that a female which lived in their basement often wandered more than half a mile away in search of food. In Michigan, Quick (1944:75) found the maximum distance traveled in one day (= night?) by a large male to be 3.43 miles although two miles was the average distance traveled by this individual. In 1942, from January 4 to March 4, in Centre County, Pennsylvania, Glover (1943B) studied tracks of 11 males and 10 females, in newly fallen snow, and ascertained that the distance traveled in a single night averaged 704 (60-2535) feet for the male and 346 (20-1420) feet for the female. The weasels in the open timber traveled farther per trip than those in the brushland and dense stands of trees.

Behavior

An adult female (now the holotype of Mustela frenata nevadensis) seen running across a field, and, I think, unaware of my presence, at every bound bent her back up so far that she reminded me of a measuring worm. For part of the time when running, the tail was held off the ground straight out behind, and then, for a while, inclined upward at an angle of about 45°. Another weasel that I saw in the daytime, and that I think was unaware of my presence, was bounding along among the Baccharis bushes on the south-facing slope of Dwight Way Canyon, Berkeley, California. This individual, at each bound, arched the back up so high as to remind me, again, of a measuring worm.

The long-tailed weasel is a land mammal and unlike its close relative, the mink, is seldom seen in the water. That it can swim, however, is attested by the capture of one while it was swimming across the Río Ramos in México (Davis, 1944:381). Also, Green (1936), in May, in Gratiot County, Michigan, saw a weasel, running with a Peromyscus in its mouth. The weasel dropped the mouse, entered the water and swam to a hole among stones.

More instances of climbing, than of swimming, have been reported in the literature for the long-tailed weasel. Seton (1929 (2):625) quotes William M. Graffius of Pennsylvania as having seen a weasel closely pursue a red squirrel nearly to the topmost branch of a large hemlock. When the squirrel loosed its hold and dropped into a stream, the weasel descended to the ground and caught and killed the squirrel when it emerged from the water. Pearce (1937:483), in central New York State, on July 29, 1931, watched a weasel chase a chipmunk up a black cherry tree ten inches in diameter, and noted that the first rush carried the weasel "straight up the trunk for approximately 10 feet, where it hesitated momentarily before continuing. Then, instead of climbing vertically, it made progress by traveling in short ascending spirals around the trunk, scarcely making 3 feet in height for each circuit of the tree. Upon reaching the limb by which the chipmunk escaped, the weasel followed out along this in the same spiral manner. This limb had a diameter of about 4 inches at its base and extended upward at an angle of perhaps 20 degrees above the horizontal . . . it made its way head first almost down to the ground, using the same spiral mode of progress, but at a leisurely pace. . . . While traveling down the side limb it appeared practically to wrap its sinuous body around the limb."

A male long-tailed weasel, from Colorado, which I kept captive was often fed freshly killed mice. These I thrust through one of the small openings in the wire mesh. The weasel quickly learned to seize any part of a mouse thus introduced and his tugging aided in getting the mouse into the cage. Occasionally a mouse too large to be got through the mesh had to be withdrawn. In such an instance, if the weasel had already had hold of the mouse, he would screech frightfully. I have heard no other vocal sounds from a weasel except a kind of purring.

The sense of smell apparently is well developed; at any rate it is keen enough to allow the weasel to follow the trail of an intended victim by the scent left by the latter. Murie's (1935:321-322) account, for example, of a weasel pursuing a snowshoe rabbit gives clear evidence that the weasel relied on scent in following the rabbit.

A captive male weasel obtained at Gainesville, Florida, stamped his hind feet when annoyed (Moore, 1945:259).

A male from Colorado that I kept for months in a cage at Lafayette, California, was several times found in a sleep so deep that he was awakened with difficulty. Seton (1929 (2):629-630) writes: "In my small menagerie, I have had half-a-dozen Weasels of the New York species. Their sleeping dens are arranged so as to be easily and silently opened. Several times I have lifted the lid to find the weasel in a deep sleep—a sleep so profound that I had to poke him vigorously with a stick before he awoke, looked up, and rushed forth with a little puff of wrath, and a little puff of smell."

Feces and urine were ordinarily deposited in one particular place by each of the captive weasels that I have observed. Hamilton (1933:294) records that a large male M. f. noveboracensis, in a week, averaged 10 evacuations every twenty-four hours, that urination immediately precedes defecation, and describes the feces as black or brown, long and narrow and often spiral-shaped owing "to the matted fur of some rodent that had been eaten." Quick (1944:77) writes, concerning four winter dens in Michigan, that "The latrines of weasels were in the entries of used dens and scats could be collected there by the handful." Polderboer, Kuhn and Hendrickson (1941:116) in the spring of 1939 at Ames, Iowa, gathered scats "from latrines found at the entrances of burrows and from latrine chambers found within burrows." Scats were found by them in the linings of some nests.

Courage of a high order might be credited to the long-tailed weasel because individuals have attacked animals much larger than the weasels. Actually, however, in few if any of these instances was the motive for attack known. That a hawk was attacked is suggested by Soper's (1919:45) account of Mustela frenata noveboracensis wherein he repeats a story told to him of a hawk observed in unsteady flight, and obviously in distress, which when it plummeted to earth was with a weasel which escaped from the observer. Charles Tatham, Jr., of Cambridge, Massachusetts, according to Seton (1929 (2): 630, 631) observed one that attacked his dog.

Persons and long-tailed weasels have figured in some rather strange encounters. For example, Oehler (1944:198) recounts that in the autumn of 1940 at Cincinnati, Ohio, an animal, mistakenly thought to be a chipmunk, was seen to dash into a hollow log whereupon pounding on the log brought out the weasel which bit and clung to the hand of one man whose companion was bitten when he attempted to free the man that was bitten first.

Seton (1929 (2): 631) writes that on the night of September 5, 1897, on Roosevelt's old ranch, near Medora, North Dakota, a man turned over his saddle (which was lying on the ground) to dislodge what was thought to be a pack-rat. The animal was a long-tailed weasel which attacked him. It ran up his legs a number of times aiming at his throat before being killed by a dog.

Criddle and Criddle (1925:146) wrote: "August 20, 1919.—A longicauda in the Insectary ran at me this morning apparently with a view to intimidating. It uttered a shrill cry while making the attack, but retreated after advancing within two feet." The same authors (op. cit.: 147) further write that a "Long-tailed Weasel was caught in a trap set for gophers, and, on being released by Miss M. Criddle, at once turned upon its liberator and bit savagely at her boot. It then moved a short distance away to a tub of water, where it drank thirstily, merely glancing at the observer from time to time while doing so, and then ran off out of sight.

"Mr. T. Criddle records a similar experience. After liberating a large weasel from a trap, it immediately rushed at him and persisted in its attack with such ferocity that it was three times picked up and thrown, on each occasion to a greater distance, before it finally abandoned its offensive.

"We have no record of a weasel making an unprovoked attack upon anyone."

Wight (1932: 164) in Michigan, detected a weasel attacking a hen. The weasel fled at Wight's approach but returned and attacked him several times. Finally the weasel went around Wight to reach the hen. In Wight's words "There was no evidence of infuriation, but rather a well directed offense at the one object, regardless of its size, which stood between the weasel and an opportunity to satisfy its desire to kill, which was probably based upon the uncontrollable urge of hunger pangs."

Weasels of each of the three North American species have been successfully kept in captivity. A type of cage satisfactory for keeping the animals in the laboratory is described by Bissonnette and Bailey (1940:761-763). Some of the captives used their teeth to break glass water-containers and to gnaw slivers of wood from the cages. Ingested slivers of wood and bits of broken glass caused the deaths of some of the captives. Weasels kept by me all were of the species Mustela frenata. They thrived on a meat diet but I was always careful to give them, every few days, if not each day, some small rodents entire, thinking that the bits of bone and fur ingested might, in some way unknown to me, keep the digestive tract in better condition than would flesh devoid of hair and bone.

Three young weasels approximately the size of mice, in the Okefinokee Swamp of Georgia, were obtained by a hunter who, according to Harper (1927:303), raised them by feeding "milk for a few days, and then fresh meat." Litters of young born in captivity have been successfully raised by the mothers (Hamilton, 1933) and success in getting the animals to breed in captivity and to rear their young is recorded by Wright (1948A). He has found, however, that the majority of his captive adult males show no interest in mating when placed with females in heat. He, therefore, uses only selected males and when a female in heat is to be bred, he places one of his responsive males with her one day, another of his responsive males with her the second day and thus alternates a couple of males for three or four days. Even so, slightly fewer than half of the females which were thus bred produced young.

A weasel in the white winter coat was used by Audubon and Bachman (1856:177, Quarto edit.) to drive rabbits out of their burrows in the same fashion that ferrets commonly are used. Although these naturalists refer to their animal as an ermine it probably was Mustela frenata noveboracensis, the long-tailed weasel. The animal's teeth (probably canines) were blunted and a long cord tied on its neck. With the aid of this weasel 12 rabbits were caught in one morning and more than 50 in four weeks.

Enemies

Little is recorded concerning enemies of weasels and it may be that other vertebrates are not an important factor in removing the annual increase. Errington (1935:195-198), in Iowa, found four, putrid weasels about dens of red foxes, Vulpes fulvus. No remains of weasels were found in the feces of the foxes and it appears that the foxes do not eat the weasels. The label on an adult female specimen of M. f. spadix from Boone County, Iowa, bears the date May 10, 1938, and the annotation, by T. G. Scott, "fox-killed." Bailey (1931:328) recounts that "Weller saw a coyote carrying one in its mouth" at an elevation of 11,500 feet in the Pecos Mountains of New Mexico. The type specimen, a young female, of M. f. peninsulae from Hudsons, Florida, according to Rhoads (1894:155) ". . . was caught in the woods by a cat." Barber and Cockerell (1898:189) mention one that was killed by a dog in Mesilla Park, New Mexico. Moore (1945:258) records the death of a weasel in Florida. Circumstantial evidence indicated that it was killed by the bite of a water moccasin. In the Biological Surveys Collection of mammals in the United States National Museum, the label with the skull of an adult male weasel, No. 160663, from Banning, California, carries the information that the skull was taken from the stomach of a Crotalus (rattlesnake).

In reporting on a study of owl predation in Delaware County, Pennsylvania, Pearson and Pearson (1947:143) mention that "weasels are found throughout the county but . . . were never eaten by the owls."

The Uinta spermophile at some places and times probably is a prey sought by the long-tailed weasel but Warren (1924:265) records Citellus armatus repeatedly chasing weasels in August, at Camp Roosevelt, Yellowstone National Park, and how the ground squirrels at one time ignored the weasel even when it came within a few inches of a squirrel.

Warren (1932:71), on August 2, 1931, at Grand Mesa, Colorado, obtained a large male weasel with two porcupine quills in it; one was near the mouth and another "in the skull." Osgood (1935:156) writes that near Rutland, Vermont, a male weasel "taken in April, was heavily parasitized and had several short porcupine quills embedded in its neck, head, and shoulders." The remainder of Osgood's account implies that the weasel may have turned to porcupine because the normal food for weasels was scarce at the time. Porcupine quills, then, are a hazard for weasels although it is unlikely that the porcupine is ever to be classed as an enemy of the weasel.

An accident of another sort, which must at the very least have been annoying to the weasel that suffered it, was recorded by Soper (1921:37). The animal had a stick lodged crosswise between the fourth upper premolar teeth.

The recorded actions of several kinds of animals which are too small to be dangerous to the weasel suggest that they recognize that the weasel is a danger to them. Borell and Ellis (1934:21) mention that a weasel in Nevada caused a great disturbance among the chipmunks. Long (1938:250) heard pikas give evidence of terror by a peculiar cry when a weasel was in a rock slide occupied by the pikas. Seton (1929 (2):629) writes "On June 14, 1915, as I prowled around the south side of the lake on my homeland at Greenwich, Conn., my attention was called to a pair of song sparrows and a male towhee that were noisily mobbing a Weasel, twittering around and darting at him, as though they knew full well his evil ways. The weasel paid little heed, but soon dived from sight in a stone wall."

No account has been found of an American weasel or ermine rolling, tumbling and frolicking in a manner that aroused the curiosity of birds to a degree which permitted the weasel to come within leaping distance of the birds. Accounts of such behavior are on record for the English stoat (ermine).

Food and Hunting

Weasels are active both in the daytime and at night. Whether the time of activity varies with the season, with the locality, with the sex or with other conditions, I do not know. Adult, live, free-living, actively moving weasels that I recall having seen all were observed in the daytime: two were in Alameda County, California, two were in White Pine County, Nevada, one was in Scotts Bluff County, Nebraska, and one was in Laramie County, Wyoming. I recall ten adults, from the same three states, and one from Washington State, that got into my traps; two of these certainly got in the traps in the night; one certainly got in the trap in the daytime; the other eight were found in traps which may have caught the weasels either in the night or in the daytime. Soper (1946:136) in speaking of M. f. longicauda north of the International Boundary in Canada remarks that it has the "habit to some extent of hunting at all times of day." Criddle and Criddle (1925:144) in writing of Mustela frenata longicauda in Manitoba record that "The shrill cry of a rabbit [Lepus americanus] in the dark is nearly always due to the weasel's attack. Indeed, we have often watched the latter at work during the twilight hours. First would come the almost noiseless run of the small rabbit with its characteristic dodging and this would be followed by the appearance of the agile foe which, at times, would leap high over obstacles and at others move swiftly beneath them. Then there would follow intermittent cries of the rabbit as the weasel secured a temporary hold of its quarry, for be it noted that this hunter apparently bites anywhere to begin with and it is probable that the blood made to flow acts as an aid to tracking as well as weakening the prey. Several similar close encounters might occur before the rabbit would be finally overcome, but weasels are very persistent when they once get into contact with their victims and it is therefore very seldom that the latter escape. In killing, they either penetrate the brain with their teeth, or dislodge the vertebrae behind the head." These and more than two score other observations which record the time when weasels were seen make it clear that some were active at night and that some were active in the daytime.

As to the routes traveled while the weasels are hunting, Quick (1944:77) says of four individuals that he studied in Washtenaw County, Michigan: "The weasels appeared to prefer hunting certain coverts with noticeable regularity, but rarely cruised the same area on two consecutive nights."

The killing technique of fifteen captive Mustela frenata noveboracensis was studied by Glover (1943A). For the weasels he released 19 mice, 3 brown rats, 6 cottontails and 4 ring-necked pheasants. Most of the mice were killed by a bite on the back of the head, with the body and legs of the weasel hugging the back of the victim. "The weasel shoved the prey in close to the stomach with the hind legs, and the kill was made in a reclining semi-curled-up position." On each of the rats (Rattus) an initial grip was secured at the base of the ear. When the rat rested, a new hold was taken by the weasel. Finally the weasel secured a hold at the base of the skull and near the ear, and a light crushing sound followed. Four of the six cottontails were killed by bites on top of the head and ear; two cottontails succumbed from neck wounds. In three instances, neither of two weasels could be induced to make a determined attack on the cottontails or to kill them. At times the cottontails proved to be able opponents for weasels by striking out with their front feet and by kicking with their strong hind legs. In killing the pheasants the teeth of the upper jaw of the weasel pierced the top of the braincase and the teeth of the lower jaw entered the region of the auditory process. The forelegs hugged the neck of the pheasant, the body of the weasel was extended in a riding position on the back of the bird and no amount of kicking or rolling dislodged the weasel.

Polderboer, Kuhn and Hendrickson (1941) describe a cottontail cached by a weasel as having the muscles of the neck severed from the region behind the right mastoid process and noted "that hemorrhage in the region of the right jugular vein had occurred."

Concerning the methods of killing mammals smaller than cottontails, the accounts by Nichols and Nichols (1935:297-299) and that by Svihla (1931) corroborate Glover's (1943A) account, as do also the accounts of Miller (1931B:164) and Moore (1945:257). The latter says that his captive male, from Gainesville, Florida, customarily bit its rodent prey at the base of the skull and used the feet to manipulate the live prey. Miller (loc. cit.) emphasized that his male weasel (M. f. longicauda) grasped where it could, used its snakelike body to coil over the prey and shifted the grip of its teeth to the nape of the neck or back of the skull. The captives that I have had [one from Salt Lake City, Utah; three from Contra Costa County, California; and the same individual reported upon by Miller (1931:150)] customarily employed the techniques of killing small rodents that were described by Glover and Miller (loc. cit.).

Allen (1938:225-229) experimented with the ability of four different males of M. f. noveboracensis from Michigan to kill adult cottontails. The method used was to place the weasel in a cage of quarter-inch hardware cloth approximately three feet long, two feet wide, and two feet high. The bottom of the box was covered with several inches of straw. One cottontail was offered to each weasel. In two instances the weasel attacked and bit the cottontail, was struck by the hind feet of the cottontail, retired from the attack and died a few hours later as a result of the blows of the cottontail's hind feet. In the other two instances the weasel rendered the cottontail helpless by severing the neck muscles from the skull. Subsequently an incision made by the weasel, in each of the two instances gave access to blood on which the weasel fed until it was full, in one instance by licking "blood as a cat laps milk." One rabbit was subdued in 10 minutes and the other in 15 minutes. Allen (op. cit.) points out that cottontails form a considerable portion of the weasel's food and thinks that they are killed in burrows more easily than they were in the cage.

In writing of the three species of weasels, including Mustela frenata, found at Treesbank and vicinity, Manitoba, Norman Criddle and Stuart Criddle (1925:143, 144), in my opinion, correctly explain the killing of more prey than weasels need. "The fact that weasels frequently kill many more animals than they require for immediate use has been universally interpreted as a lust for killing—a supposition which we believe to be quite erroneous. It is true that weasels often kill more than they need, but the surplus is not necessarily wasted because the animals always store it for future use, in much the same way as do badgers, minks or skunks, and with the same object in view as squirrels have in gathering nuts. We have observed many such stores, but as far as our observations go, the habit of killing in excess occurs much more prominently in the late summer and autumn months than in the spring. Indeed, we have no records of excessive spring slaughter and this indicates that the supposedly blood-thirsty habit of weasels is no more a lust for killing than is the woodsman's foresight in providing his larder with meat for the winter months. It should be noted in this connection that members of the weasel family, when undisturbed, do not leave their victims scattered about, but carefully store them away, and in many instances the bodies are buried with earth or taken under ground to preserve them. We suspect that this instinct for preserving food for future use accounts for most of the excessive killing by carnivorous animals instead of this latter indicating an aimless desire for slaughter which would unnecessarily deplete the food supply of the future. This instinct, however, does not seem to be as definite as that of some rodents, and there is no doubt that much of the stored meat decays before it can be utilized."

Criddle and Criddle (1925:146) note that a weasel in the vicinity of Treesbank was carrying a rat [Rattus] and that "Two small punctures in the throat were the only evidence of the manner in which its death had been brought about."

Considerable information has been recorded concerning the food of Mustela frenata and a little information is on record as to kinds of foods not taken that could have been taken. For example, Ingles (1939:253, 254) on May 14, 1938, near Shasta City, California, noted that nestlings of russet-backed thrushes were ignored by an adult weasel and four young weasels which were feeding instead on meadow mice and a mole. Howard (1935:322, 323) records that a weasel in Michigan which carried bits of meat from beef bones on a porch ignored a red squirrel which drew on the same food supply but which retreated to the end of the porch when the weasel appeared. Quick (1944) records that in the winter of 1940 on a 640 acre area in Washtenaw County, Michigan, four resident weasels did not kill any of the 10 rabbits or several pheasants but subsisted on smaller animals. Glover (1943A) thought that M. frenata kills only a few adult cottontails in the wild. To judge from these observations, M. frenata chooses small mammals as prey in greater measure than it does birds or larger mammals.

Records of prey taken, attacked or pursued by Mustela frenata include the following:

Broad-footed mole (Scapanus latimanus).—One was fed on by an adult M. frenata and four young, on May 14, 1939, "near Shasta City," California (Ingles, 1939:253, 254).

Dusky shrew (Sorex cinereus).—A female weasel, at Majestic, Long Island, N. Y., was shot when carrying a Sorex cinereus that had a small hole in the top of its head (Nichols and Nichols, 1935:297-299).

Big short-tailed shrew (Blarina brevicauda).—One was taken from the stomach of a weasel (Hamilton, 1928:249).

Townsend ground squirrel (Citellus townsendii).—Alcorn saw a weasel five miles west of Fallon, Nevada, carrying a squirrel (Hall, 1946:192).

Richardson ground squirrel (Citellus richardsonii).—The attempted capture of one of these squirrels in Saskatchewan is recorded by Seton (1929 (2):625).

Belding ground squirrel (Citellus beldingi).—Grinnell, Dixon and Linsdale (1937:233) recount that at Tuolumne Meadows, California, a weasel killed a ground squirrel of this species.

Thirteen-lined ground squirrel (Citellus tridecemlineatus).—Errington (1936:406, 407) found a den in Palo Alto County, Iowa, on June 22, 1934, where he collected 32 fecal pellets. Sixteen samples contained thirteen-lined ground squirrels, 9 contained rabbits, 9 contained mice (7 Microtus, 1 Peromyscus and 1 unidentified); red-winged blackbirds and unidentified fringillids were represented as also were ground beetles, grasshoppers and other insects. One red-winged blackbird lay near the entrance of the den.

Franklin ground squirrel (Citellus franklinii).—Sowls (1948:126) records that at Delta, Manitoba, a weasel was observed killing one of these squirrels and that "the weasel had taken the squirrel from its hibernating burrow as evidenced by tracks in the snow." On July 19, 1917, in the vicinity of Treesbank, Manitoba, T. Criddle saw a weasel attacking one of these ground squirrels which was in mortal terror and squeaking continuously. Eventually the squirrel was thrown on its back "and would have been speedily killed but for an interruption" (Criddle and Criddle, 1925:146).

Golden-mantled ground squirrel (Citellus lateralis).—On August 15, 1941, along the Kaweah River in Sequoia National Park, Boyer (1943:99, 100) saw a weasel chasing a Citellus lateralis; three or four times the weasel grasped the back of the neck of the squirrel which each time threw off the weasel until the two, weasel after the squirrel, plunged into the river. The squirrel, bleeding at the base of the skull, was rescued and entered a hole; the weasel got out of the water and under a rotting log. Follett (1937:365) at 2 p.m. in Plumas County, California, saw a weasel have hold of the lower jaw of a golden-mantled ground squirrel near its throat. Alcorn watched a weasel chase a golden-mantled ground squirrel in Nevada (Hall, 1946:192) and Grinnell and Dixon (1919:681) record that on August 4, 1911, near Monache Meadows in eastern Tulare County, California, a weasel pursued, captured and killed a golden-mantled ground squirrel.

Eastern chipmunk (Tamias striatus).—Pearce (1937:483) in central New York State, on July 29, 1931, saw a chipmunk scamper up a tree pursued by a weasel.

Chipmunk (subgenus Neotamias).—Stanford (1931:363) on November 11, 1931, at Fish Lake, Utah, saw a weasel pursuing a chipmunk. On August 5, 1910, "near Independence Lake," Nevada County, California, Louise Kellogg recorded that a weasel seized and ran off with a chipmunk (Grinnell, Dixon and Linsdale, 1937:233). Allen (1938:228) observed that a chipmunk (whether Tamias striatus or T. minimus not specified) was killed in 30 seconds whereas 10 to 15 minutes were required by the caged, male Mustela frenata noveboracensis to kill a cottontail.

Red squirrel (Tamiasciurus).—Seton (1929 (2):625) records the capture of one in Pennsylvania, and Grinnell, Dixon and Linsdale (1937:232), at Cisco, California, saw one closely pursued by a weasel.

Flying squirrel (Glaucomys).—Burroughs (1900:77, 78) records remains of one of these squirrels along with the remains of other animals in a food cache of a Mustela but his account does not make clear whether Mustela frenata or Mustela erminea was the species of weasel involved.

Northern pocket gopher (Thomomys).—In "July, 1939, near Stillwater [Nevada], Alcorn pursued . . . [a] weasel and caused it to drop . . . a pocket gopher [Thomomys bottae] which was about two-thirds grown" (Hall, 1946:192). Grinnell, Dixon and Linsdale (1937:233) write that "at least twice, weasels in the [Yosemite] Valley were seen carrying pocket gophers." Relative to Thomomys talpoides in the vicinity of Treesbank, Manitoba, Criddle and Criddle (1925:146) record that on September 11, 1918, an individual of Mustela frenata longicauda took seven pocket gophers dead. . . . It seized the rodents by the middle of their back and held them high while carrying them away. They were stored in a gopher burrow some two hundred yards distant. On February 17, 1921, "Came across the marks of a weasel carting some object over the snow. An investigation revealed a recently-killed pocket gopher with its captor still in possession." Criddle (1930:279), at Aweme, Manitoba, "frequently observed this weasel [M. f. longicauda] . . . carrying a pocket gopher to its larder, and twice it has been encountered in mid winter with freshly killed gophers in its possession." The evidence already presented that weasels levy heavily on pocket gophers is strengthened by the many references in the literature to weasels having been caught in traps set for pocket gophers in the burrows of those rodents and by the many statements, not quoted here, that living quarters of weasels are in burrows made originally by pocket gophers. For example, the present writer, in an account of the Mammals of Nevada (Hall, 1946:191, 192), has said of the long-tailed weasel, Mustela frenata nevadensis, that "All the three dens that were excavated . . . were originally burrows of pocket gophers. . . . Although we have found weasels in many situations in Nevada, . . . they most often were obtained from the burrows of pocket gophers." Excluding the weasels taken by Alcorn, more specimens of the remaining lot were caught in traps set in the burrows of pocket gophers than by all other means combined. All of the 22 weasels taken by Alcorn [within a radius of 10 miles of Fallon] were obtained in gopher traps.

Mexican pocket gopher (Cratogeomys).—At Chalchicomula, 8000 feet, Puebla, Nelson (1918:470 and letter dated March 9, 1928) saw a weasel fastened to a pocket gopher. Nelson obtained the pocket gopher and found that its neck muscles were torn loose from the skull.

Grasshopper mouse (Onychomys).—Barber and Cockerell (1898:189) found remains of this mouse in the stomach of a weasel at Mesilla Park, New Mexico.

White-footed mice (Peromyscus).—Green (1936) saw a weasel in Gratiot County, Michigan, in May, carrying a Peromyscus. Quick (1944:76), in winter, in Michigan, found one dead, probably killed by a weasel. From Washtenaw County, Michigan, Quick (1944:77) examined 294 scats of free-living weasels and found Peromyscus in 189 scats, Microtus in 83, small birds in 20, red squirrel in 3, and hair of weasels in small quantities (probably from the animals which deposited the scats) in 36. He concludes (op. cit., 78) that the winter food was 65 to 70 per cent Peromyscus, 23 to 33 per cent Microtus, and 2 to 7 per cent small birds.

Wood rats (Neotoma).—A female long-tailed weasel weighing 250 grams was taken one mile north of Kent, Texas, while eating a Neotoma albigula (Davis and Robertson, 1944:263). A wood rat house under observation by Vestal (1937:364) in Contra Costa County, California, was invaded by one weasel which ate two adult wood rats (Neotoma fuscipes) and one young. In the same area he saw a weasel in a wood rat nest some months later (Vestal, 1938:5). Three miles east of Reno, Nevada, on May 13, 1936, W. B. Richardson watched a long-tailed weasel carrying a half-grown round-tailed wood rat (Neotoma lepida) across a rock slide (Hall, 1946, 192). Harper (1927:303) records three wood rats [Neotoma floridana] and two cotton rats [Sigmodon hispidus] found dead in the den of a female weasel and her three young in the Okefinokee Swamp of Georgia. Another female and three young approximately half grown were found in the swamp in a hollow pine log. Contents of the den as described to Harper were nearly a peck of wood rats, whole and in pieces; remains of several kinds of birds including robins and quail, and a piece of joint snake (Ophisaurus ventralis).

Meadow mice (Microtus).—Polderboer, Kuhn and Hendrickson (1941), in 1939, at Ames, Iowa, identified "A total of 118 items . . . in 97 winter scats and 48 in the 38 spring scats." Their combined data are as follows:

Polderboer, Kuhn and Hendrickson divide their data into two categories, winter and spring. Items recorded in winter but not in spring are house mouse, tree sparrow, and grasshopper. Items recorded only in spring were pocket gopher and least weasel. The samples of cottontail and least weasel all were from the scats of one large male weasel. Of a total of 14 pheasants, 24 quail and 35 cottontails on the 160 acres involved in the study only two cottontails appear to have been killed by the weasels—really by one weasel of four which lived on the area.

Food items taken from the nests (3) and adjacent caches of food in the dens, were as follows: meadow mouse, 30; short-tailed shrew, 4; pocket gopher, 2; deer mouse, 2; least weasel, 1; tree sparrow, 1. The authors remark that the abundance of several prey species does not cause the weasels to ignore the shrews which are said to be distasteful to carnivores.

Two horned larks, apparently killed by weasels, were found on the 160 acre area studied; the horned larks were not in caches of food, nor were remains of horned larks found in scats.

Dearborn (1932:34, 37) for Michigan, on the basis of contents of (37?) intestinal tracts and "feces collected partly in winter and partly in summer" found that, by frequency of occurrence, mammals comprised 83 per cent of the food, birds 10 per cent and insects 7 per cent. Frequency indices for the genera of mammals in percentages of food items of all kinds were as follows: Microtus, 31 per cent; Peromyscus, 24 per cent; Sylvilagus, 14 per cent; Sorex, 7 per cent; Blarina, 5 per cent; Scalopus, 2 per cent.

Criddle and Criddle (1925:146), for the vicinity of Treesbank, Manitoba, record that on October 3, 1913, a weasel was seen to take a field mouse down a hole. They add (op. cit.:147) that "Once while ploughing, we observed a Long-tailed Weasel carrying a field mouse. . . ." Ingles (1939:253, 254), in June, 1938, near Mt. Shasta City, California, found an adult and four young weasels which fed on several Microtus montanus montanus. Green (1936) in May, in Gratiot County, Michigan, in the vicinity of a nest in which there were four young weasels, found "several" dead Microtus. Hamilton (1933:330) records that in New York State a male weasel, on April 5, 1932, at Ithaca, had eaten a Microtus and that in May, 1927, a female weasel was seen carrying a Microtus in its mouth.

Hamilton's (1933:333) study of the contents of the digestive tracts of bodies of weasels obtained from fur trappers and fur buyers enabled him to publish the following "Frequency Indices of Mammal Genera in Fall and Winter Food of 163 Mustela noveboracensis": Microtus, 33.6 per cent; Sylvilagus, 17.3; mammals undetermined to genus but principally mice, 17.1; Peromyscus, 11.3; Rattus, 9.1; Blarina, 5.9; Sciurus, 2.7; Tamias, 1.0; Condylura, 0.8; Ondatra, 0.8.

Grinnell, Dixon and Linsdale (1937:233, 234) quote W. Fry concerning a weasel which reared six young at Giant Forest, California, in 1919, as follows: "This parent weasel, after the birth of her young, remained at the premises for a period of thirty-seven days; during which time, from actual count, the following numbers of mammal species fell victim to her: mice [genera not specified] 78; gophers 27; moles 2; chipmunks 34; wood rats 3; ground squirrels 4. This is a total of 148 animals for the . . . thirty-seven days . . . not a bird was captured during the period."

Rats (Rattus).—Criddle and Criddle (1925:146), on the farm at Treesbank, Manitoba, record a long-tailed weasel, on July 2, 1918, running away from the farm buildings carrying a rat; July 11, 1919, "Two longicaudas . . . have been seen running off with rats on several occasions."; July 11, 1920, "There are two large weasels about the buildings[;]. . . . Each has been noted with rats and this afternoon one of them was seen running into the woods carrying a rat, followed by two excited swallows." The authors (op. cit.:147) add "In the fall of 1924, Mr. A. Cooper, a prominent poultryman of Treesbank, observed a large weasel carrying a freshly killed rat which it stored below ground and then returned towards the poultry-house, causing no little apprehension to the owner. Within a short time, however, the weasel reappeared with another rat which it hid as before. In this way several rodents were accounted for during the afternoon, and Mr. Cooper assures us that the weasel 'kept up the good work for some days'." Hamilton (1933:330) in New York State in May, 1927, saw a male weasel in possession of a rat.

Big jumping mouse (Zapus major).—In the Warner Mountains of California, on Parker Creek, H. C. Bryant frightened a weasel that dropped a freshly killed jumping mouse (Grinnell, Dixon and Linsdale, 1937:232).

Snowshoe rabbit (Lepus americanus).—Adolph Murie (1935:321-322) writes that: "Four miles north of Funkley, Minnesota, early on the morning of November 13, 1921, . . . watched from the top of a 30-foot spruce a weasel. .. hunting a varying hare. . . . The ground was covered with six inches of fresh snow . . . both animals . . . [had] their [white] winter pelage.

"My attention was first attracted to the hare as it came hopping steadily but unhurriedly from the north. Directly in front of me, about 75 feet from the tree I had climbed, the hare crisscrossed back and forth at various angles over an open area about 20 feet in diameter. After producing a maze of tracks, the hare 'froze' near one edge of the pattern. In a few minutes the weasel appeared, all his faculties focused on the warm trail. Expertly he followed its convolutions, passing at times within a few feet of the watching hare. Not until the weasel had followed every turn of the trail to within three feet of its termination did the hare skip off. It came out to the road almost directly below me, turned at right angles northward and was soon out of sight. At the road the weasel lost the trail, . . . and then ran parallel with it, once more in hot pursuit.

"Ten minutes later the hare emerged from the north as before, came on directly to the tracked-up area, and continuing its stratagem, leisurely hopped about to leave its zigzag trail. Then it sat down quietly to wait. . . . The weasel['s] . . . nose led him through the network with little trouble. He was almost upon the hare before it jumped off and followed the same path [as] . . . before. . . .

"The hare had to show his big heels [a third time] . . . as the weasel approached him. This time the weasel failed to follow. . . . After examining a few brush heaps he vanished into the woods behind me."

Seton (1929 (4):723, 724) writes that in December of 1886 in the sandhills northeast of Carberry, Manitoba, he saw a weasel chasing a snowshoe rabbit which took refuge near his feet under the sleigh and so escaped the weasel. Thurber (1940:356) mentions a month-old varying hare that was rescued from a weasel and of approximately the same size as the weasel.

Criddle and Criddle (1925:146) for the vicinity of Treesbank, Manitoba, record "August 21, 1921.—Heard cries of a small rabbit at dusk to-night, which investigation showed was being attacked by a large weasel. The rabbit was later carried to the weasel's store chamber below ground." They record further (op. cit., 146, 147): "November 8, 1924.—Shot a bush rabbit and left it lying. Two hours later [it] . . . was found to have been dragged beneath a brush pile and partly eaten. Innumerable weasel tracks left no doubt as to the identity of the thief." In describing a weasel that wintered in a nest in a threshing machine, the same authors (op. cit.:143) say that no bird remains were found in the pile of approximately three pounds of droppings adjacent to the nest. In a store chamber some 140 yards away from the nest, two bush rabbits (Lepus americanus) had been dragged to the entrance and numerous smaller rodents were taken below ground. The rabbits were buried beneath the snow and eaten as necessity arose. Narrow selectivity on the part of the weasel in choosing food is almost always shown in instances where the food of weasels has been studied. For example, the weasel which lived in the threshing machine ate rodents and rabbits and not poultry although the weasel had ready access to the poultry building. The weasel which lived in the bag of feathers in the basement of Stuart Criddle's house ignored grouse, approximately 20 in number, in favor of other non-avian food.

Cottontail (Sylvilagus).—Polderboer, Kuhn and Hendrickson (1941) mention that one of 4 weasels which they studied on a 160 acre area at Ames, Iowa, in 1939, had a cache of food in a pocket gopher burrow 10 rods distant from the weasel's den. The cache contained only two cottontails, one partly eaten. Leopold (1937) records seeing a Mustela (probably a long-tailed weasel but possibly an ermine) kill a third-grown cottontail by biting it at the base of the skull. Leopold describes the blood sucking or licking, suggesting that he shared the popular misconception that weasels suck blood. The supposition that weasels suck blood has been refuted by many observers, for example by Svihla (1931). My own observation of captives makes me think that weasels do not suck blood. Seton (1929 (2):626) quotes B. H. Warren as seeing a weasel dragging a freshly killed, still warm, rabbit that contained nine embryos almost ready for birth. A young rabbit was seen being carried by a weasel in Hidalgo County, Texas, in March, 1935 (Mulaik, 1938:104). An instance of a cottontail being chased in June in South Carolina is recorded by Hamilton (1933:330). Addy (1939:372, 373), in Virginia, on August 14, 1939, shot a large weasel which was pursuing a Sylvilagus that was only a foot and a half ahead of the weasel. The rabbit stopped when a shot was fired and permitted itself to be stroked and petted. Tracking showed that the weasel had chased the rabbit for a half mile. On November 20, 1942, at Lake James, Indiana, a weasel was seen by Grosjean (1942:443) attacking a "young rabbit" in the throat of which the weasel had made five large holes from which there was no obvious bleeding. Seton (1929 (4):798) recounts that in 1910 at Base Lake, Michigan, F. C. Hicks saw a cottontail with a weasel hanging to its legs rush to the cottage. When only four feet from Hicks the weasel loosed its hold and the cottontail escaped under the cottage. Burroughs (1939:253) on May 14, 1939, in Saginaw County, Michigan, records that a young cottontail weighing between 200 and 250 grams was carried from the nest and killed. Burroughs was attracted first by the "hissing scream" of the weasel, strode toward the sound, flushed an adult cottontail, and discovered the empty nest from which the weasel had taken the young cottontail.

Brush rabbit (Sylvilagus bachmani).—Vestal (1937:364) in Contra Costa County, California, found a brush rabbit that appeared to have been killed by a weasel.

Reptiles.—Grinnell, Dixon and Linsdale (1937:234) recount that in July, 1889, in Wilson Canyon, near Pasadena, California, a weasel killed a red racer by severing the backbone of the snake. In April, 1935, in Hidalgo County, Texas, a half grown bull snake (Pituophis sayi sayi) was regurgitated by a young weasel. Russell (1930:504, 505) has recorded finding in California a male weasel and a king snake (Lampropeltis getulus boylii) three feet five inches long in mortal combat. The weasel killed the snake but the weasel, incapacitated by the conflict, was easily picked up by hand and was also saved as a specimen.

Wild birds.—In the spring of 1940, in Washtenaw County, Michigan, one bobwhite, of 10 bobwhite living on a 640 acre area, was killed by one of four weasels that lived on the area. No other quail was killed there. The one unfortunate bird was killed in the mouth of an abandoned den where the quail roosted (Quick, 1944:76). A male weasel, subspecies M. f. effera, was seen by Booth (1946:439) attempting to enter the nesting hole of a pair of flickers, Colaptes. One song sparrow (Melospiza melodia), and one slate-colored junco (Junco hyemalis) were recorded by Quick (1944:76) as killed by weasel in Michigan.

Chicken (genus Gallus).—Quick (1944:78) writes that in one year (1938-1939) weasels were reported to have killed 1.03 per cent of all chickens in one township of Washtenaw County, Michigan, and that of the total damage to all kinds of poultry, 59 per cent was done by weasels. Weasels entered 19 per cent of the chicken coops on the study area. Farmers killed 68 per cent of the weasels seen in barn yards. Spring and summer were the seasons in which most of the weasels were observed in barn yards. Internal evidence in Quick's (op. cit.) account leads me to suspect that some losses of poultry were charged to weasels when Rattus was actually responsible.

Criddle and Criddle (1925:146), quote a neighbor in the vicinity of Treesbank, Manitoba, as recording that on October 29, 1917, "A weasel last night made its way into our fowl-house, the door being inadvertently left open. The weasel killed eleven fowl, some of which were dragged into the yard. All the largest fowls were selected, the pullets remaining untouched though they were in the majority. Next night the weasel dug a hole beneath the building and killed a hen and two cocks, returning for another during the day, making a total of fourteen in all." Criddle and Criddle (1925:146) remark that the weasel proved to be a large one, probably an old male. The same authors (op. cit.:147) record that at their farm at Treesbank, Manitoba, on January 31, 1925, "A Long-tailed Weasel killed three hens last night, and rather severely bit a cock about the neck. This, or another weasel, had been around the farm-yard for sometime (The specimen was a large male). . . .

"In the fall of 1924, Mr. A. Cooper, a prominent poultryman of Treesbank, observed a large weasel carrying a freshly killed rat which it stored below ground and then returned towards the poultry-house, causing no little apprehension to the owner. Within a short time, however, the weasel reappeared with another rat which it hid as before. In this way several rodents were accounted for during the afternoon, and Mr. Cooper assures us that the weasel 'kept up the good work for same days'.

"Being a farmer of many years' standing, Mr. Cooper has naturally lost some poultry through the agency of weasels, but while he remarks that 'there are good as well as bad actors among weasels', he has the practical good sense to recognize the value of an efficient ratter even though it be a weasel.

"Our sister, Maida Criddle, writes under date of March 4, 1925:

"'There is another weasel (longicauda) in the fowl-house, a well-behaved one this time. It came and took a piece of meat out of my hand quite nicely, which it carried down a hole and then came and sniffed all over my mitt to see if there was any more. I thought it had been killed when I visited the farm buildings next day as there was a strong smell of musk on the cat and in the fowl house, but the weasel was there as cheeky as ever. It got hold of my skirt twice and tried to pull me down its hole. I think it wanted the cloth for a bed, as it was taking straw and other material down the burrow. The poultry were very frightened at first, but they are getting used to the weasel's presence now'."

In commenting on the economic role of the long-tailed weasel in Manitoba, Criddle and Criddle (1925:145) write as follows: "Supply and demand are prominent factors in governing our weasels' food habits. The two smaller species, as we have already pointed out are so dependent upon mice for a living that they increase or diminish with the fluctuation of these creatures. The Long-tailed Weasel, however, is not so easily checked by the temporary disappearance of any particular kind of game. If mice are scarce it devotes greater attention to gophers or bush rabbits and if these are not in sufficient numbers to satisfy its appetite, the animal raids a poultry house as a last resource. In nine years out of ten, this weasel will find sufficient food about the fields and woods, but on the tenth it may be obliged to temporarily turn to domestic animals. It is at such times that the weasel is seen and its deeds recorded. A thousand mice may have been killed in the meantime, but the destruction of half a dozen hens is alone used as evidence of the weasel's economic standing.

"In the last twenty years we have permitted weasels to frequent the farm buildings at will and the poultry house has been no exception. In that time rats and mice suffered severely from the weasels, while the total number of poultry taken were six. Many times that number, however, have been killed by rats.

"When we review our experiences of the past, we are astonished to find what few poultry have been killed by weasels. Our own losses in forty-two years have not exceeded fifteen birds and even these were usually eatable. There have been reports of losses from time to time from neighbors, but on looking into details we find that there are very few farmers who have experienced more than three separate occasions of weasel depredation and the total loss per farmer in the last thirty years does not, we are sure, exceed ten birds. This is surely a remarkably small payment to weasels in general for the great good done by them in killing rodents.

"We wish to point out, too, that only the exceptional weasel becomes a poultry killer. In most cases apparently it is a fully-grown male that does the killing. There are exceptions, of course, but when we see a large weasel actively engaged in rodent hunting within a few feet of a brood of newly hatched chickens and not even looking at them, we must at least pause to ask if this animal is the enemy that we were taught to believe it to be."

A suggestion that weasels sometimes obtain the prey killed by hawks is offered by Criddle and Criddle (1925:147) who write: "Hawks are not always the aggressors, as is shown by an incident reported by Mr. H. L. Seamans, of Lethbridge, Alberta. Mr. Seamans noted a large buzzard suddenly fly straight upwards from a fence post, and then alight upon another one some distance away. A little while afterward this bird once more arose in the same manner as before, and presently repeated the performance again. An investigation then followed and revealed that a Long-tailed Weasel was following the hawk from post to post.

"We should hardly expect a weasel to attempt to capture a bird of the above type. On the other hand, it is possible that these animals might be able to startle a hawk sufficiently to cause it to drop its prey, which would thus provide food for the weasel."

The following frequency index is compiled from the foregoing data on prey of Mustela frenata.

More significant than the above compilation, of course, are the results of careful studies of the food of the long-tailed weasel in restricted areas. Examples of such studies are those of Polderboer, Kuhn and Hendrickson (1941) and Hamilton (1933:333).

According to Hamilton's (1933:332) observations on captive weasels, "There seems to be little relative difference in the amount they eat, regardless of their activities.

"In general, more food is taken in summer than in winter. Usually about a third their weight every 24 hours is eaten, but a growing young weasel will consume much more. A young male noveboracensis, weighing 145 grams, consumed an entire chipmunk, fur and bones, weighing 85 grams, in 24 hours. A day later it ate all of a partly grown rat, 105 grams, in the same length of time."

Moore (1945:253) records that a captive male that he obtained at Gainesville, Florida, consumed, on the average, between 63 and 70 grams of flesh and blood per day. The weasel itself weighed approximately 320 grams.

Sanderson (1949:413), concerning seven young weasels from Manitoba, that he raised in captivity, writes: "From the fifth to the seventh week of age, they consumed approximately 22 per cent of their body weight per day; from the eighth to the tenth week (just before reaching mature size) they consumed approximately 24 per cent; but after reaching maturity they consumed only 18 per cent. When given all the food they would take in one day, they ate as much as 40 per cent of their body weight."

Criddle and Criddle (1925:143, 146) say that weasels drinking at a bird trough "held their mouths very close to the water and as far as we could see, lapped the liquid up with rapid movements of the tongue. As a rule, after drinking, they would merely spring to the ground and vanish amid a bunch of scolding birds, but occasionally we have seen an animal slowly drag itself through the water and follow this performance by some rapid gambols, or a quick run, a method of drying which most of us have practiced in our youth." According to Hamilton's (1933:332) observations on captives, "Weasels are great drinkers, and while they take but little at a time, about 25 c.c. is drunk by a large animal during a day. . . ."

Reproduction

Philip L. Wright's several papers (1942A, 1942B, 1947, 1948A, and 1948B) reporting on his detailed studies of Mustela frenata (subspecies oribasus and longicauda) in captivity have yielded a large share of the precise information that we have concerning breeding and reproduction in this species. He has found that a single litter, of up to 9 young is born in the spring, usually in April. At three months of age the females "are full grown." The young males remain sexually immature during the first summer but the young females, as well as the females which are more than a year old, come into heat in the midsummer and are bred by the adult males. After a long period of quiescence lasting for several months, the embryos resulting from these matings become active in early spring and develop to full term in less than 27 days after they become implanted. The adult males are sexually active from April into August, when the testes are at maximal size and are conspicuous in the scrotum. A gradual regression takes place starting in August and extending into September. By October the testes may be fully regressed and the molt to white may start in this month. The white winter weasel, of either sex, is sexually inactive. The testes of the sexually active male in early spring and late summer are seven to eight times the size of the fully regressed testes. Females which had borne and suckled young were first found to be in oestrus 65 to 104 days after birth of the young. Lactation lasts for approximately 5 weeks. In 18 litters the length of the gestation period varied from 220 to 337 days with an average of 279 days. The female in heat has the vulva much swollen and she will remain in this condition for several weeks if not bred. Wright (1948A) describes the actual mating as beginning with a scuffle after which the male grabs the female by the scruff of the neck with his teeth and holds her until she becomes subdued when he clasps her lower abdomen with his front feet and arches his back over her posterior regions. The two animals remain locked in this position usually for two hours and sometimes for longer than three hours. If the animals are left together, copulation may take place again on the same day or upon succeeding days.

Hamilton (1933:316-321) writes of a freshly born M. f. noveboracensis that it ". . . was pink and much wrinkled. The wetness . . . did not entirely obscure a few sparse, rather long, white hairs . . . over its back and head. It had the pronounced and extraordinarily long neck of the adult." At one day of age the average weight of six individuals in the litter was 3.1 grams, which is 3 per cent of the weight of the adult female and 1-1/2 per cent of the weight of an adult male. At two weeks of age "The silky white hair . . . obscures the general flesh color of the skin, evident a week earlier. The hair on the back of the head and neck, also over the shoulders, is slightly longer than that of the back . . ." but there is no crest or mane or pompadour at this or any other age such as characterizes the juvenal ermine. When 21 days old one young male "hurried from the nest chamber and commenced to eat some meat." At three and a half weeks "They are all eating small pieces of meat. . . . The canine teeth have made their appearance in both the upper and lower jaw, but just a hint of the incisors show. Some of the cheek teeth are through, as the meat appears to be thoroughly masticated by the little ones." On the 36th and 37th days the eyes opened. Sanderson (1949:415) found that a litter of seven young of Mustela frenata longicauda, from Manitoba, raised in captivity, "reached the peak of their growth" at approximately ten weeks of age.

Several nests have been found. In Manitoba, Sanderson (1949:412) excavated a burrow at the mouth of which he had trapped the adult female and in which he found eight young approximately five weeks old. The "burrow was about three inches in diameter, with two chambers at a depth of twelve inches. One of these was empty, the other contained the young. The two surface-openings were but two feet apart and the entire burrow was no more than three feet long. . . . The meager nest material consisted entirely of finely chopped grass. There was no mouse hair present, no accumulation of fecal material, and no storehouse containing food."

Charles O. Handley has written me that on January 25, 1929, on the Sinkola Plantation, Thomas County, Georgia, he investigated the living quarters of a family of five weasels, four of which had been shot five days before by a hunter. According to the hunter each of the four which had been killed was approximately two-thirds the size of one which escaped into a hole in the ground. Handley found that the weasels had been using as headquarters a burrow in the trunk of an old uprooted oak as well as a nearby gopher burrow. The burrow in the oak was approximately ten feet long and had been excavated in the rotten wood. In a distance of fifty feet along the gopher tunnel there were several used openings with pathways leading away from each. On February 6, Handley, with the help of a friend, trapped a large male weasel near this place.

Criddle and Criddle (1925:143) describe a female which, one winter, slept in a bag of feathers in a basement of a house occupied by one of the authors; another weasel in winter made its headquarters in a threshing machine. The nest of the latter "was somewhat roughly constructed and consisted of a convenient bunch of straw and chaff under the cylinder."

Harper (1927:303) in the Okefinokee Swamp of Georgia dislodged a weasel from the house of a wood rat and was told of a den found in the swamp "in the trunk of a hollow cypress tree" from which a mother weasel and three young "about the size of mice" were obtained. "The bed contained, I suppose, a bushel or more of rabbit hair, rat hair, and squirrel hair. It looked like it must have been used as a den for several years, although there was no stink that I could detect except the musk from the old Weasel." Another female and three young approximately half grown were found in a hollow pine log.

Between January 6 and April 12, 1940, on 640 acres of land, in Washtenaw County, Michigan, four weasels were studied and each weasel used only one den in this period (Quick, 1944:78). Criddle (1930:279) remarks that M. f. longicauda at Aweme, Manitoba, often makes its temporary headquarters in the burrows of pocket gophers (Thomomys). A female and three young weasels were found by Shaw (1921:167) using a nest of a mountain beaver in the burrow of that animal. Green (1936), in May, in Gratiot County, Michigan, saw a weasel enter a hole under a decayed log and investigated finding four young weasels in a nest mostly of Microtus fur.

In the early part (winter and spring) of 1939, at Ames, Iowa, Polderboer, Kuhn and Hendrickson (1941) studied four weasels living in four separate dens on 160 acres typical of Iowa farmland and excavated three of the dens. One den was in a weed patch in an old mole run. The nest chamber, approximately nine inches in diameter and six inches below the surface of the ground "was filled with grasses packed in a layer-like formation. In the center of this mass was a nest hollow lined with patches of mouse and shrew fur. Beneath this layer of fur and at the sides of the nest were skins, various bones, and skulls of partially eaten mice and shrews . . . scats [were in the nest]. . . . At intervals, layers of clean grass had been laid over the filth of the former bed, thus giving the nest a stratified appearance." A second den, of a large male, was in a field of sweet clover two feet high in the former burrow of a Franklin's ground squirrel. The nest cell, seven inches in diameter and nine inches below the surface of the ground, "was lined with grasses mixed with much rabbit and mouse fur. Some scats, and bones and fur of mice and shrews were matted together in layers at the bottom of the nest." When this den was abandoned the male weasel occupied, for a month, another burrow, 20 rods distant, of a Franklin ground squirrel, in the field of sweet clover. The nest cell measured 11 by nine inches and was 11 inches below the surface of the ground. "Two nest layers were present. The first, composed chiefly of coarse straw and grass, had apparently been occupied at some time by a spotted skunk. . . . On top of the skunk nest was the weasel nest composed of fine grasses, mouse fur, and skeletal remains of mice."

Relation of the Sexes to each other and to the young

Quick (1944:75) writes that on March 28, in Michigan, he found the tracks of a male and those of a smaller animal, supposedly a female, meeting. The two "then led along the fence for about 18 chains and both entered the den of the male. . . . Only the tracks of the smaller weasel left the den on the same date. Observation on April 12 showed that the large male still occupied the den." I am at a loss to explain this behavior since breeding would not be expected to occur in late March and since I suppose that the male and female do not live together except in the breeding season. Consequently, I wonder if the sign was wrongly read.

Fig. 29. Map showing the geographic ranges of the subspecies of Mustela frenata and Mustela africana.

1. M. f. noveboracensis  2. M. f. occisor  3. M. f. primulina  4. M. f. arthuri  5. M. f. olivacea  6. M. f. peninsulae  7. M. f. spadix  8. M. f. longicauda  9. M. f. oribasus 10. M. f. alleni 11. M. f. arizonensis 12. M. f. nevadensis 13. M. f. effera 14. M. f. washingtoni 15. M. f. saturata 16. M. f. altifrontalis 17. M. f. oregonensis 18. M. f. munda 19. M. f. xanthogenys 20. M. f. nigriauris 21. M. f. latirostra 22. M. f. pulchra

23. M. f. inyoensis 24. M. f. neomexicana 25. M. f. texensis 26. M. f. frenata 27. M. f. leucoparia 28. M. f. perotae 29. M. f. macrophonius 30. M. f. goldmani 31. M. f. tropicalis 32. M. f. perda 33. M. f. nicaraguae 34. M. f. costaricensis 35. M. f. panamensis 36. M. f. meridana 37. M. f. affinis 38. M. f. aureoventris 39. M. f. helleri 40. M. f. macrura 41. M. f. agilis 42. M. f. boliviensis 43. M. a. africana 44. M. a. stolzmanni

Hamilton (1933:328), however, writes that M. f. noveboracensis is to "be found in pairs when caring for the young. During mid-May, 1927, I several times saw a male of this species carrying food to a den of young ones." Green (1936), in May in Gratiot County, Michigan, remarks that while he was uncovering and examining a nest of four young weasels, two adults ran about excitedly and one removed a young weasel. In instances where several nearly full-grown young have been obtained from one den it has been my experience (Hall, 1946:191) that the only adult trapped there was the female; no adult male was found or in the one instance when found he was living alone in a den 200 yards away from the den of the female and her young. Data are too few to warrant a definite conclusion about the extent to which the male aids in rearing the young, but I have wondered if he might not do so when the young were less than half grown and then live alone when they were more than half grown.

Mustela frenata noveboracensis (Emmons)

Long-tailed Weasel

Plates 16, 17, 18, 31, 32 and 33

Putorius Noveboracensis Emmons, Quadrupeds of Massachusetts, p. 45, 1840.

Mustela fusca DeKay, Zool. of New York, Pt. 1, Mammalia, p. 34, 1842.

Putorius fuscus Audubon and Bachman, Journ. Acad. Nat. Sci. Philadelphia, 8 (Pt. 2):288, 1842; Audubon and Bachman, Vivip. quadrupeds of N. Amer., 3:234, pl. 148, 1853 (pl. 1848).

Putorius noveboracensis, DeKay, Zool. of New York, Pt. 1, Mammalia, p. 34, 1842; Baird, Mamm. N. Amer., p. 166, 1858; Merriam, N. Amer. Fauna, 11:16, pl. 4, figs. 1, 1a, 2, 2a, pl. 5, figs. 3, 3a, text figs. 4-6, 30, June 30, 1896; Bangs, Proc. Biol. Soc. Washington, 10:13, pl. 1, figs. 2, 2a, pl. 2, figs. 2, 2a, and pl. 3, figs. 3, 3a, February 25, 1896; Cory, Mamm. Illinois and Wisconsin, p. 366, plates, 1912.

Putorius erminea, Audubon and Bachman, Vivip. quadrupeds of N. Amer., 2:56, pl. 59, 1851.

Putorius agilis Audubon and Bachman, Vivip. quadrupeds of N. Amer., 3:184, pl. 140, 1853.

Putorius richardsonii, Baird, Mamm. N. Amer., p. 164, 1858 (part).

Putorius (Gale) erminea, Coues, Fur-bearing animals, p. 109, 1877 (part).

Putorius noveboracensis notius Bangs, Proc. New England Zool. Club, 1:53, June 9, 1899. Type from Weaverville, Buncombe County, North Carolina.

Mustela noveboracensis noveboracensis, Miller, U. S. Nat. Mus. Bull., 79:97, December 12, 1912; Soper, Journ. Mamm., 4:251, November 1, 1923.

Mustela cicognanii, Henninger, Journ. Mamm., 2:239, November 29, 1921; Seton, Lives of game animals, 2:584, 1929 (part, Ohio); Hamilton, Amer. Midland Nat., 14:290, July, 1933 (part, Ohio); Lyon, Amer. Midland Nat., 17:109, January, 1936 (part, Ohio).

Mustela noveboracensis, Jackson, Journ. Mamm., 3:15, February 8, 1922.

Mustela frenata noveboracensis, Hall, Carnegie Instit. Washington Publ., 473:104, November 20, 1936; Hall, Amer. Midland Nat., 18:304, March, 1937.

Type.—Williamstown, Berkshire County, Massachusetts. Type specimen not known to be in existence.

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Range.—Altitudinally, sea level to highest parts of mountains of eastern United States; Canadian Life-zone of Ontario and Quebec southward through eastern United States in Canadian, Transition and Upper Austral life-zones to and including upper edge of Lower Austral Life-zone in the Carolinas and northern parts of Georgia, Alabama, and Mississippi; westward from the Atlantic Coast to St. Croix and Mississippi rivers. See figure 29 on page 221.

Characters for ready recognition.—Differs: From M. f. olivacea, in males, by width of tympanic bulla which is less than rather than more than 8.5 mm., and in adult females by total length which is less than rather than more than 345 mm. and by mastoid breadth which is less than rather than more than distance between articular faces of exoccipital condyle and glenoid fossa; from M. f. occisor by a number of average differences including smaller size, relatively shorter tail and relatively narrower skull (see measurements); from M. f. spadix by least width of color of underparts amounting to less than 41 per cent of greatest width of color of upper parts, absence of color of underparts on ankles and feet, adults with hind foot less than 50 in males and 40 in females, orbitonasal length less than 15.5 in males and 13.5 in females, length of tooth-rows less than 18.0 in males and 15.7 in females, mastoid breadth less than 25.5 in males and 22.0 in females; from M. f. primulina in males by interorbital breadth averaging more than 24 per cent of basilar length, orbitonasal length averaging more than 34 per cent of basilar length or 64 per cent of mastoid breadth, tympanic bullae less inflated anteromedially, than posteromedially, and in females by orbitonasal length amounting to more than two-thirds of mastoid breadth, by zygomatic breadth averaging less than 21, and by anterolateral margin of tympanic bullae not projecting below squamosal; from M. f. arthuri in males, by zygomatic breadth more than distance between anterior palatine foramen and anterior margin of tympanic bulla and by convex dorsal outline of skull in longitudinal axis.

Description.—Size.—Male and Female:

The length of the hind foot averages more than the basal length in males whereas the reverse is true in females. The tail, relative to the length of the body, is longer in males than in females. The average differences in external measurements of the two sexes in Massachusetts, are: total length, 104; length of tail, 42; length of hind foot, 12.1. In Michigan, where the males are smaller, corresponding differences are only, 65, 33, and 11. Weight of 19 adult males from New York (Hamilton, 1933:294), 225 (196-267) grams and in 13 adult females, 102 (72-126) grams. Weights of 2 adults from Michigan are: ♂ 258; ♀ 101 grams.

Externals.—Longest facial vibrissae black, brown, or white (often all three colors in same specimen) and extending beyond ear; carpal vibrissae same color as underparts and extending to apical pad of fifth digit; hairiness of foot-soles as shown in figure 19.

Color.—Upper parts, in summer, Vandyke Brown or darker than tone 4 of Burnt Umber of Oberthür and Dauthenay, pl. 304. Sometimes approaching tone 2 of Warm Sepia of Oberthür and Dauthenay, pl. 305. Underparts, in summer, ranging from white through Napthalene Yellow (Peterboro, N. Y.), Pale Orange Yellow (eastern Mass.), near Primuline Yellow (unusual specimen from Leelanau Co., Mich.) to near (c) Deep Chrome (no. 19053, U. S. Nat. Mus., Roan Mts., N. C.) In winter, all white except tip of tail, or upper parts near (12" 1) Rood's Brown and tone 2 of Raw Umber of Oberthür and Dauthenay, pl. 301, with underparts white or sometimes tinged with yellowish. Tip of tail at all times black. Upper parts of uniform color except for occasional slight darkening of nose. Color of underparts extends distally on posterior sides of forelegs to foot and sometimes over upper sides of toes and on medial sides of hind limbs only to knees. Least width of color of underparts averaging, in a series of twenty-two males, mostly in full winter pelage, from Liberty Hill, Connecticut, 21 (11-40) per cent of greatest width of color of underparts. In eleven females from the same place, corresponding percentages are 20 (14-29). Black tip of tail in same series of males, most of which are in full winter pelage, 70 (60-75) mm. long; thus longer than hind foot and averaging 50 per cent of length of tail-vertebrae.

Skull and teeth.—Male (based on ten adults from Massachusetts): See measurements and plates 16-18; weight, 3.6 (3.3-4.4) grams; basilar length, 44.6 (43.3-46.0); zygomatic breadth less than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla; mastoid breadth less than postpalatal length; postorbital breadth more or less than length of upper premolars and greater than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more or less (usually more) than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less than length of tympanic bulla; least width of palate less than length of P4; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 3 to 6 upper incisors; height of tympanic bulla more or less than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer or shorter than rostrum; anterior margin of masseteric fossa behind or directly below posterior fourth of m1.

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Female (based on five adults from Mass.): See measurements and plates 31-33; weight, 1.7 (1.2-2.1) grams; basilar length, 36.5 (35.2-38.1); zygomatic breadth less than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth more or less than length of upper premolars and more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; least width of palate more or less (usually less) than greatest length of P4; tympanic bulla as far posterior to foramen ovale as width of 4 to 5-1/2 upper incisors; height of tympanic bulla less than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer than rostrum.

The skull of the female averages 53 per cent lighter than that of the average male.

Comparisons of the skull with those of M. f. olivacea, M. f. spadix, M. f. primulina, and M. f. arthuri, are made in the accounts of those subspecies. As compared with that of M. f. occisor the skull of adult male noveboracensis, is of smaller average size with relatively (to basilar length of Hensel) lesser mastoid and zygomatic breadths. In addition to the zygomatic arches of noveboracensis being less widely bowed outward they seem to be more rounded posteriorly. Comparisons of subadult females indicate that these differences exist in the females as well as in the adult males.

Remarks.—The earliest of the post-Linnaean references to this weasel mostly were under the specific name erminea in the belief that the American animal was the same as the larger of the two common species of weasel in the Old World. The name noveboracensis, now in use for this subspecies, was applied in 1840 and since that time the males usually have borne that name; the females, because they are smaller, were more frequently confused with some other species. Audubon and Bachman in 1853 even proposed the name agilis for the female in the mistaken belief that it was a species distinct from the male. After 1896, when Bangs correctly classified the weasels of the eastern United States, the males have been correctly identified and the females, except by a few authors, likewise have been correctly named. Because many early American naturalists did their first collecting of mammals in the geographic range of noveboracensis, the person who examines labels of specimens of this subspecies can find data written in the hand of Spencer Fullerton Baird, Theodore Roosevelt, and other naturalists famous for their work as scientists or accomplishments otherwise. The material is more nearly adequate than is that of many other subspecies and the number of specimens is exceeded—and only slightly—by that of the subspecies nevadensis, which like noveboracensis has a relatively large geographic range.

Intergradation with Mustela frenata spadix is indicated by subadult males from western Wisconsin, namely, one from Gordon, three from Colfax and one from Meridean. Linear measurements of the teeth of these specimens are exactly intermediate between those of spadix from Elk River, Minnesota, to the west, and noveboracensis from, say, Beaver Dam, Wisconsin, to the east. The specimens from western Wisconsin show approach to spadix also in that the length of the tooth-rows and breadth of the rostrum are slightly greater than in noveboracensis from farther east, say, Beaver Dam, Wisconsin.

Indeed, animals from as far east as Beaver Dam itself might be thought of as showing some approach to spadix. Although, along the eastern seaboard, the upper lips, with rare exceptions, are the same color as the underparts, farther west, in Michigan and Wisconsin, the lips more often than not are white. Animals from Beaver Dam have slightly shorter black tips on the tails, broader extent of the light color of the underparts and females average slightly larger than typical noveboracensis, say, those from Massachusetts. Each of these differences reflects characters found better developed in the spadix-longicauda stock to the west.

Toward the southern part of its range where noveboracensis meets M. f. olivacea there is a marked increase in yellowness of the underparts. This coloration of the underparts, since it is not so well marked in the northern part of the range of noveboracensis, might be regarded as showing intergradation with olivacea and primulina, each of which has far more intensely colored underparts than does noveboracensis. Excepting this increase of yellow on the underparts, however, there are few if any characters of noveboracensis which undergo marked change as approach to the range of olivacea is made. Indeed, the characters of noveboracensis remain constant to within a relatively short distance of the geographic range of olivacea.

Notwithstanding the state of affairs described above, intergradation seems to take place. Three specimens referred to noveboracensis but which at the same time are regarded as intergrades with olivacea are as follows: No. 28.300, Charleston Museum, from five miles east of York, South Carolina, is an adult female with a badly crushed skull. In external measurements the specimen agrees with noveboracensis. The underparts, as regards color and width, are intermediate. The general proportions of the skull and tympanic bullae agree with those of noveboracensis but the skull is larger than in any female of true noveboracensis and approaches that of olivacea. The same can be said of a young female, no. 80, Ohio State Museum, from Roswell, Georgia.

Another female, no. 171559, U. S. Nat. Mus., from Lookout Mountain, 1500 ft., Fort Payne, Alabama, is barely subadult. The external measurements are nearer those of olivacea. The color and narrowness of the underparts are typical of noveboracensis. The proportions and especially size of the skull show approach to olivacea, though they are nearer to noveboracensis when all features are taken into account. In the northern part of its range individuals of noveboracensis attain larger size than farther south. This tendency reaches its extreme, in males at least, in M. f. occisor of Maine. Specimens of noveboracensis from the Adirondacks of New York average larger (see cranial measurements on page 418) than those from farther south, and thus approach occisor in size as well as in geographic position. Also, occasional individuals which strongly show characters of occisor are found even farther south than the Adirondacks of New York. This is true of no. 96518, U. S. Nat. Mus., ♂ ad., from Lunenburg; Massachusetts. The animal has a large skull of relatively great width much as in occisor, although its external measurements, relative length of tail and long, terminal, black brush place it with noveboracensis rather than with occisor. Of a pair of specimens from Ossipee, New Hampshire, the male, no. 77108, U. S. Nat. Mus., has a long (175 mm.) tail, and short (60 mm.) black pencil as in occisor, although otherwise it is referable to noveboracensis. Still another specimen, a subadult male, no. 4193, Mus. Comp. Zoöl., from Upton, Maine, has a longer (51 mm.) hind foot than noveboracensis although it otherwise agrees with that subspecies. As remarked by Bangs (1899:55), other than fully adult specimens from the range of occisor are "troublesome," and would not be selected as distinct from noveboracensis if placed in a series of that subspecies, say, from New York State. In view of the facts that several specimens from intermediate localities combine the characters of noveboracensis and occisor, that noveboracensis in the northern part of its range averages larger than it does farther south and thus approaches occisor in size, and that occasional large specimens resembling occisor in several, but not all, features sometimes crop up in the northern part of the range of noveboracensis, it appears that noveboracensis and occisor intergrade. Therefore they are treated as two subspecies of the single species, Mustela frenata.

Intergradation with M. f. primulina has been commented on in the discussion of that subspecies. Female, no. 159980, U. S. Nat. Mus., from Golconda, Illinois, has many characters of primulina but two young males from there agree better with noveboracensis.

Examination of 283 adult and subadult skulls for malformation of the frontal sinuses revealed only ten that were not obviously malformed. Two were from New York, one from Massachusetts, one from Pennsylvania, and six from the 52 specimens from Michigan and Wisconsin. In addition, skulls of many young and even juveniles were malformed.

Specimens examined.—Total number, 555, arranged alphabetically by states and provinces and, unless otherwise noted, from north to south by counties in each state. Except as otherwise noted specimens are in the United States National Museum.

Alabama. DeKalb County: Fort Payne, 1.

Connecticut. Litchfield County: Riverton, 1[5]; Gaylordsville, 1. Hartford County: East Hartford, 4 (3[5]); Glastonbury, 2[5]; South Glastonbury, 4[5]. Windham County: Plainfield, 2 (1[14]). Fairfield County: Greenwich, 2[2]. New London County: Liberty Hill, 35 (33[75], 2[7]).

District of Columbia. Washington, 3; near Washington, 1; Eastern Branch, 1; Congress Heights, 1; Benning, 1; no definite locality, 1.

Georgia. Towns County: Young Harris, 1. Cherokee County: Canton, 1. Cobb County: Roswell, 1[81].

Indiana. St. Joseph County: Notre Dame, 2[99]. Porter County: Hebron, 1. Miami County: Denver, 5 (4[75], 1[4]). Wells County: Bluffton, 1. Howard County: Russiaville, 1. Jay County: Salamonia, 1[2]. Boone County, 1[2]. Knox County: Bicknell, 3.

Illinois. Lake County: Camp Logan, 3[60]; Fort Sheridan, 1[60]. Cook County: W Northfield, 2; Flossmoor, 1[60]; no locality more definite than county, 1. Du Page County: Bloomingdale Spg., 1[60]. Carroll County: Savanna, 1[87]. McLean County: Normal, 1[7]. Champaign County: Harwood Township, 1[7]. Pike County?: Milton Spring, 1[60]. Pope County: Golconda, 3.

Kentucky. Woodford County: Midway, 1. Hancock County: Hawesville, 1.

Maine. Oxford County: Upton, 1[75]; Bethel, 1[74].

Maryland. Howard County: Long Corner, 1; Hanover, 1. Montgomery County: Gaithersburg, 1; Garret Park, 1; Chevy Chase, 1; Bethesda, 1. Prince Georges County: Laurel, 18; Plummer Island, 3; Oxon Hill, 1. Talbot County: Easton, 1. Dorchester County: Cambridge, 5[40].

Massachusetts. Middlesex County: Wilmington, 6; Burlington, 6; Lexington, 1[75]; Wayland, 2[75]. Berkshire County: New Marlboro, 1[5]. Worcester County: Lunenburg, 2; Lancaster, 1[75]; Princeton, 2[75]. Norfolk County: So. Weymouth, 1[75]. Plymouth County: Wareham, 5[75].

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Michigan. Marquette County: Michigamme, 1. Charlevoix County: Thumb Lake, 1[76]; 1/2 mi. N Thumb Lake, 1[76]. Leelanau County: Leland, 3[76]; Duck Lake, 2 mi. S Leland, 1[76]; Lost Pond, 8-1/2 mi. S Leland, 1[76]. Osceola County: Le Roy, 2[76]. Huron County: Rush Lake, 1[76]. Saginaw County: East Saginaw, 1. Oakland County: Royal Oak, 4[76]; South Lyon, 1[76]. Livingston County: Portage Lake, 1[76]. Washtenaw County: Portage Lake, 6[76]; Waterloo, 2[14]; Lima, 1[76]; Ann Arbor, 11[76]; 3 mi. E Ann Arbor, 1[76]; 2 mi. SE Ann Arbor, 1[76]; 2 mi. S Ann Arbor, 1[76]; 3 mi. S Ann Arbor, 1[76]; Dixboro, 1[76]; Pittsfield, 3 (2[76]); Saline, 1[76]; near Saline, 2[76]; 1 mi. S Saline, 2[76]; York, 2[76]; Manchester, 2[76]. Lenawee County: Morenci, 1[76]. Cass County: Marcellus Township, 1[76]. Berrien County: Harbert, 1[76]; Warren Wood Preserve, 1[76]; Warren Woods, 1[76].

New Hampshire. Grafton County: Franconia, 1[2]. Carroll County: South Chatham, 4 (3[5]); Ossipee, 2; Intervale, 1[5]. Merrimack County: Webster, 2[75].

New Jersey. Morris County: Morristown, 1. Essex County: West Orange, 1[2]. Mercer County: Princeton, 1[1]. Ocean County: Point Pleasant, 1[2]. Camden County: Haddonfield, 1[1]. Cumberland County: Millville, 2[74].

New York. St. Lawrence County: Ogdensburg, 1[74]. Clinton County: Rouses Point, 1[80]. County?: Adirondacks, 12. Essex County: Elizabethtown, 1; Schroon Lake, 1; no locality more definite than county, 1. Lewis? County: Locust Grove, 4; Lyons Falls, 1. Warren County: Lake George, 6; Caldwell, 1. Hamilton County: Beaver Brook, 1/2 mi. above mouth Indian Lake, 1[80]. Oswego County: Scriba, 2[74]; Palermo, 1[74]. Monroe County: Penfield, 3. Madison County: Peterboro, 6 (2[75]). Schoharie County: Schoharie, 1[2]. Rensselaer County: East Shodack, 1[80]. Tompkins County: Taughannock Falls, 2[58]; Ithaca, 4 (3[58]); Glenside, Ithaca, 1[58]; 6 mi. Creek, Ithaca, 1[58]. Green County: Lanesville, 1[2]. Orange County: Poplopen's Pond, 1[2]; Highland Falls, 1[2]. Putnam County, 1[19]. Westchester County: Sing Sing, 4; Armonk, 1[2]; Hastings, 3 (2[2], 1[19]). Nassau County: Flushing Meadows, 1[2]; Flushing, 1[58]; near Flushing, 1[2]; Oyster Bay, 2. Long Island: Cold Spring Harbor, 1; Bridgehampton, 1[2]. County in question: Severance, 3; Lake Grove (Long Island?), 1.

North Carolina (east to west by counties). Wake County: Raleigh, 4 (1[2], 1[75], 2[76]). Mitchell County: Magnetic City, foot of Roan Mountain, 6; Roan Mt., 1; Roan Mt., 6000 ft., 3. Buncombe County?: Valley of Black Mts., 1[2]. Madison County, 2[11].

Ohio. Trumbull County: Warren, 1[93]. Seneca County: Tiffin, 1[81]. Summit County: Ira, 2[81]. Crawford County: Galion, 1[81]. Ashland County: Loudonville, 1[76]. Auglaize County: New Bremen, 3[81]. Franklin County: 3 mi. N Columbus, 1[81]; Minerva Park, Columbus, 5[81]. Fairfield County: Sec. 32, Pleasant Twp., 1[81]; Lancaster, 1[81]. Clinton County: Reesville, 1; 1/2 mi. S and 1/2 mi. W Wilmington, 2[74]. Pike County: Waverly, 1[81].

Ontario. Sudbury District: Metagama, 2[86]. Carleton County: Ottawa, 2[77]. Muskoka County: Lake of Bays, 1; Bracebridge, 1. Haliburton County: Gooderham, 1[60]. Simcoe County: Orillia, 4 (2[2], 2[60].) Prince Edward County: Bloomfield, 1[77]. York County: Toronto, 1[2]. Waterloo County: Branchton, 3[60]; Preston, 2[77]; no locality save county, 1[60]. Welland County: Ridgway, 1[14]. Elgin County: St. Thomas, 1[77]. Essex County: Kingsville, 1[77]; Point Pelee, 1[77].

Pennsylvania (east to west by counties). Crawford County: Pymatuning Swamp, 3-1/2 mi. W Linesville, 1[9]; Meadville, 2[9]. Beaver County: Beaver, 1[9]; Raccoon Creek, 1[9]. Butler County: Mars, 1[9]; Leasuresville, 4[9]. Allegheny County: Allegheny, 1. Warren County: Bear Lake, 2[9]. Westmoreland County: Kingston, 1[9]; Laughlinstown, 2[9]. Somerset County: Confluence, 1[9]; Tub Mill Run, 2 mi. N Springs, 1[9]. Jefferson County: Siegel, 1[9]. Clearfield? County: Penfield, 1[9]. Cambria County: Cresson, 1[9]. Fulton County: Well's Tannery, 1[9]. Clinton County: near Round Island, 2[1]. Cumberland County: Carlisle, 1. Snyder County: 5 mi. S Selinsgrove, 1. Northumberland County: Pottsgrove, 1. Union County: Mifflinburg, 1. Sullivan County: Lopez, 7 (4[1], 3[74]). Chester County: Westtown, 1[1]; Valley Forge, 1[1]; W Bradford Township, 1[1]; no locality more definite than county, 3. Philadelphia County: Holmsburg, 2[1]. Bucks County: 1[1]. Pike County: Milford, 1.

Rhode Island. Providence County: Chepachet, 1. Washington County: Lake Warden, 2.

Quebec. Megantic County: Black Lake 1[77]. County in question: Meach Lake, 1[77].

South Carolina. York County: 5 mi. E York, 1[11]. Laurens County: Laurens, 1[39].

Tennessee. Campbell County: Highcliff, 1. Carter? County: Roan Mts., 1[2]. Hamilton County: Walden Ridge, near Soddy, 3.

Vermont. Windsor County: Hartland, 1[2].

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Virginia. Shenandoah County: Toms Brook, 1. Arlington County: Arlington, 1; Ballston, 1; Alexandria, 1. Fairfax County: Falls Church, 3; Mt. Vernon, 2; no locality more definite than county, 1. Prince William County: Occoquan, 1. Essex County: Montague, 1. Prince George County, 1. Norfolk County: Wallaceton, 1. Grayson County: Mt Rogers, 3. County in question: Dismal Swamp, 1; Massanutten Mt., 1.

West Virginia. Hardy County, 1. Pendleton County: radius of 2 mi. Smoke Hole, 1[74]. Greenbriar County: White Sulphur, 2[60].

Wisconsin. Douglas County: Gordon, 1[102]. Vilas County: Mamie Lake, 4. Dunn County: Colfax, 4[102]; Meridean, 1[102]. Door County: state game farm, 17[102]; no locality more definite than county, 1[102]. Dodge County: Rolling Prairie, 1[50]; Beaver Dam, 52[50]. Dane County: Wingra Lake, 1[102]. Waukesha County: Pewaukee, 2[102]. Racine County: Waterford Township, 2[102]. Rock County: Milton, 1[102]; Bowers Lake, 1[102]. Walworth County: Lane's Mill, 8 mi. N Elkhorn, 7 (1[102], 6[54]); Delavan, 7.

Mustela frenata occisor (Bangs)

Long-tailed Weasel

Plates 16, 17, 18, 31, 32 and 33

Putorius occisor Bangs, Proc. New England Zool. Club, 1:54, June 9, 1899.

Mustela occisor, Miller, U. S. Nat. Mus. Bull., 79:98, December 31, 1912.

Mustela frenata occisor, Hall, Carnegie Instit. Washington Publ. 473:104, November 20, 1936.

Type.—Male, adult, skull and skin; no. 9102, coll. of E. A. and O. Bangs in Mus. Comp. Zoöl.; Bucksport, Hancock County, Maine; January 15, 1899; obtained by Alvah G. Door but measured and sexed by O. Bangs.

The skin is well made and in good condition. It is in full, white winter-dress with black-tipped tail. The skull has the posterior half of the left zygomatic arch broken away; otherwise the skull is unbroken and complete. Left I3 and right P3 are missing. The teeth otherwise all are present and entire.

Range.—Maine; possibly north locally to south side of St. Lawrence River in Quebec and possibly occurring in western New Brunswick. Zonal range Canadian and probably Transition. See figure 29 on page 221.

Characters for ready recognition.—Differs from M. f. noveboracensis by a number of average differences including larger size, relatively longer tail and relatively wider skull (see page 225, and measurements on pages 418, 419).

Description.—Size.—Male: Five adults yield average and extreme measurements as follows: Total length, 443 (430-465); length of tail, 163 (154-175); length of hind foot, 50 (47-54). Tail averages 58 per cent as long as head and body. Length of hind foot averages more than basal length.

Female: Measurements of two subadult female topotypes are as follows: Total length, 346, 318; length of tail, 116, 110; length of hind foot, 39, 35.5.

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Tail amounts to 50 per cent and 54 per cent of body-length respectively. Length of hind foot more or less than (about equal to) basal length.

The average differences in external measurements of the two sexes are: Total length, 111; length of tail, 50; length of hind foot, 12.5.

Externals.—As described in Mustela frenata noveboracensis.

Color.—As described in Mustela frenata noveboracensis except that black tail-tip in series of 10 males in full winter pelage 60 (45-80) mm. long; thus averaging 39 per cent of length of tail vertebrae.

Skull and teeth.—Male (based on 3 adults): See measurements and plates 16-18. As described in Mustela frenata noveboracensis except that: Weight, 4.2 (4.1-4.3) grams; basilar length, 45.7 (44.9-46.9); zygomatic breadth more or less than (about equal to) distance between anterior palatine foramen and anterior margin of tympanic bulla; least width of palate rarely less than length of P4; anterior margin of masseteric fossa behind or directly below posterior half of m2.

Female (based on 2 subadults): See measurements and plates 31-33. As described in Mustela frenata noveboracensis except that: Weight, 2.0 (1.9-2.1) grams; basilar length, 37.3, 38.2.

Comparison of the skull with that of M. f. noveboracensis is made in the account of that subspecies.

Remarks.—Excepting a specimen in the Academy of Natural Sciences of Philadelphia, obtained in 1893, and two in the Boston Society of Natural History, obtained in 1925, I have seen no material of this subspecies in addition to that examined by Bangs at the time he prepared the original description in 1899.

Anderson (1945:56, 57) records a specimen, Canadian National Museum Catalogue Number 18426, from Kamouraska County, Quebec, as of this subspecies and thinks that occisor occurs north of Maine "locally to south side of lower St. Lawrence River in Quebec; probably also in western New Brunswick."

So far as the available material of occisor permits one to judge, it is distinguished from noveboracensis by a combination of characters no one of which invariably can be relied upon as diagnostic. Employing adult males, average differences indicate that M. f. occisor is larger in each of the external and cranial measurements; tail relatively longer; black tip of tail relatively shorter; mastoid and zygomatic breadth relatively greater and zygomatic arches more nearly square posteriorly.

Considering the large number of specimens of noveboracensis which are available in comparison with the few of occisor it is not surprising that some noveboracensis should be found which exceed in size those of occisor. This is the case as regards the basilar length of a very old male, no. 96518, U. S. Nat. Mus., from Lunenburg, Massachusetts. Also, the skull is actually broader than any of those of occisor. However, this specimen is much older than any occisor examined. In a female, no. 4260, Mus. Comp. Zoöl., from Liberty Hill, Connecticut, the skull is longer (but narrower) than in either of the two available females of occisor.

The average differences pointed out above which characterize this extreme northern population of noveboracensis-like weasel in comparison with true noveboracensis without much question are geographic variations. Whether or not these variations are of a degree sufficient to warrant nomenclatural recognition is debatable. With equally scanty material from other regions I have not named variations seemingly as great as those shown by occisor. The paucity of material of occisor is a handicap in making a decision in this instance.

Each of the adult and subadult specimens, except the one from Perry, shows malformation resulting from the infestation of the frontal sinuses with parasites.

Specimens examined.—Total number, 18, listed by counties from west to east and unless otherwise indicated in the Museum of Comparative Zoölogy.

Maine. Oxford County: South Andover, 2 (Boston Soc. Nat. Hist.); Umbagog Lake, 1. Franklin County: Seven Pd. Township, 1. Piscataquis County: Grenville, [= Greenville?], 1. Hancock County: Bucksport, 10. Washington County: 3rd Mopang Lake, 1 (Acad. Nat. Sci. Phila.); Perry, 1 (Boston Soc. Nat. Hist.). County in question: Moosehead Lake, 1.

Mustela frenata primulina Jackson

Long-tailed Weasel

Plates 16, 17, 18, 31, 32 and 33

Mustela primulina Jackson, Proc. Biol. Soc. Washington, 26:123, May 21, 1913.

Putorius noveboracensis, Baird, Mamm. N. Amer., p. 166, 1858 (part).

Mustela longicauda longicauda, Dice, Journ. Mamm., 4:108, May 9, 1923.

Mustela longicauda primulina, Linsdale, Journ. Mamm., 9:141, May 9, 1928.

Mustela frenata primulina, Hall, Carnegie Instit. Washington Publ. 473:104, November 20, 1936.

Mustela frenata, Leopold and Hall, Journ. Mamm., 26:143, July 19, 1945.

Type.—Male?, young, skull and skin; no. 168006, U. S. Nat. Mus., Biol. Surv. Coll.; 5 miles northeast of Avilla, Jasper County, Missouri; May 11, 1905; obtained by Hartley H. T. Jackson; original no. 7869X.

The skin lacks the distal part of the tail—the part which bears the black tip. Otherwise the skin is complete and well preserved. The teeth of the permanent dentition all are present and entire. The lower jaws are complete and unbroken. The skull is broken transversely through the interorbital region, transversely through the braincase and longitudinally through the basioccipital. Both zygomatic arches are gone. The type is judged to be a male rather than a female as stated by the original describer, Jackson (1913:123), whose measurements of hind foot, interorbital constriction, maxillary tooth-row, and mandibular tooth-row agree with those of males and are larger than those of any female seen of this subspecies.

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Range.—Upper and Lower Austral life-zones west of the Mississippi River in Missouri and Arkansas, the southeastern half of Iowa, eastern half of Kansas and Oklahoma, northern Louisiana and northeastern Texas. Southern and southwestern limits of range undetermined. See figure 29 on page 221.

Characters for ready recognition.—Differs from M. f. noveboracensis in males by interorbital breadth averaging less than 24 per cent of basilar length, orbitonasal length averaging less than 34 per cent of basilar length or 64 per cent of mastoid breadth, tympanic bullae as much inflated anteromedially as posteromedially, and in females by orbitonasal length amounting to less than two-thirds of mastoid breadth, by zygomatic breadth averaging more than 21 mm., and by anterolateral margin of tympanic bulla projecting below squamosal; from M. f. spadix by least width of color of under parts amounting to less than 40 per cent of greatest width of color of upper parts, by absence of color of underparts on hind leg below knee, and by smaller size (hind foot less than 50 in males and 40 in females; orbitonasal length less than 15.5 in males and 13.5 in females; length of tooth-rows less than 18 in males and 15.7 in females; mastoid breadth less than 25.5 in males and 22 in females); from M. f. longicauda by Brussels Brown rather than near (h) Clay Color of upper parts, least width of underparts less than 40 per cent of greatest width of color of upper parts, absence of color of underparts on hind leg below knee, zygomatic breadth less than 28.8 in males and 24.1 in females; from M. f. neomexicana by Brussels Brown rather than Buckthorn Brown color of upper parts, in absence of white frontal spot and broad white bands on sides of head, in anterolaterally rounded, rather than "square," tympanic bullae and in zygomatic breadth of less than 30 in males and 24 in females; from M. f. frenata and M. f. texensis by absence of white facial markings and smaller size (basilar length of adult males less than 47, tail-length less than 155 in males, and hind foot less than 40 in females); from M. f. arthuri by less evenly spreading zygomatic arches (see pls. 16, 17 and 18), greater inflation of the tympanic bullae anteromedially and more nearly straight (less convex) dorsal outline of skull.

Description.—Size.—Male: Eighteen adults and subadults from Douglas County, Kansas, yield average and extreme measurements as follows: Total length, 397 (371-440); length of tail, 133 (120-147); length of hind foot, 43 (40-47). Tail averages 50 per cent as long as head and body. Length of hind foot averages less than basal length. Corresponding measurements, originally taken in inches and fractions thereof, of 9 adults and subadults from Boone County, Arkansas, are as follows: 413 (384-438); 138 (127-155); 41 (38-44).

Female: Six adults and subadults from Douglas County, Kansas, yield average and extreme measurements as follows: Total length, 339 (317-355); length of tail, 107 (95-115); length of hind foot, 35 (34-37). Tail averages 46 per cent of length of head and body. Length of hind foot less than basal length. Corresponding measurements, originally taken in inches and fractions thereof, of 5 adults and subadults from Boone County, Arkansas, are as follows: 355 (332-397); 113 (101-127); 33 (29-38).

The average differences in external measurements of the two sexes, in Douglas County, Kansas, are: Total length, 58; length of tail, 26; length of hind foot, 8. An adult male from Boone Co., Iowa, weighed 293 grams.

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Externals.—Longest facial vibrissae black or dark brown (often both colors in same specimen) and extending beyond ear; carpal vibrissae colored either like underparts or upper parts and extending to apical pad of fifth digit; hairiness of foot-soles as shown in figure 20.

Color.—Upper parts, in summer, Brussels Brown to near (14 n) Brussels Brown, or tones 2 to 4 of Raw Umber of Oberthür and Dauthenay, pl. 301. Chin and rarely upper lips white. Remainder of underparts Picric Yellow to Primuline Yellow. In winter, color essentially the same except for smoke-gray effect in upper parts and more whitish in underparts. Tip of tail at all times black. Upper parts of uniform color except for occasional darkening of nose and mid-dorsal region. Color of underparts extends distally on posterior sides of forelegs onto antipalmar faces of toes, on medial sides of hind legs only to a point between knee and ankle. Least width of color of underparts averaging, in a series of 21 males from Lawrence, Kansas, 23 (9-35) per cent of greatest width of color of upper parts. Black tip of tail in same series, most of which are in full winter pelage, 52 (40-70) mm. long; thus longer than hind foot and averaging 39 per cent of length of tail-vertebrae.

Skull and teeth.—Male (based on ten adults from Douglas County, Kansas): See measurements and plates 16-18; weight, 3.7 (3.3-4.2) grams; basilar length, 44.8 (43.8-46.0); zygomatic breadth more or less (less in 80 per cent) than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior end of tympanic bulla (less in 70 per cent); mastoid breadth more or less (less in 80 per cent) than postpalatal length; postorbital breadth less than length of upper premolars and, except in one specimen, more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more or less (less in 70 per cent) than distance between foramen opticum and anterior margin of tympanic bulla; breadth of rostrum less than length of tympanic bulla; least width of palate less than outside length of P4 (except in one specimen); anterior margin of tympanic bulla as far posterior to foramen ovale as width of 2-1/2 to 5 upper incisors; height of tympanic bulla more (except in one specimen) than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer (except in one specimen) than rostrum; anterior margin of masseteric fossa behind or just below posterior eighth of m1.

Female (based on 5 adults and subadults from Douglas County, Kansas): See measurements and plates 31-33; weight, 2.2 (2.0-2.4) grams; basilar length, 38.9 (37.6-40.7); zygomatic breadth less than distance between condylar foramen and M1 or than between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth less than length of upper premolars and except in one specimen, more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; least width of palate less than greatest length of P4; tympanic bulla as far posterior to foramen ovale as width of 3 to 5 upper incisors; height of tympanic bulla more or less than distance from its anterior margin to foramen ovale; length of tympanic bulla more than length of lower molar and premolar tooth-row and longer than rostrum.

The skull of the female averages 41 per cent lighter than that of the male.

Compared with the skull of M. f. noveboracensis from Massachusetts, that of the male of primulina, in dorsal view, is seen to be shorter anteriorly to the postorbital processes and to have a more marked postorbital constriction. In lateral view the dorsal outline of the skull of primulina is less concave in the postorbital region. In ventral view the skull of primulina is seen to be wider across the mastoid processes and zygomatic arches but the most pronounced difference is in the tympanic bullae. In noveboracensis each bulla is scooped out on the anterior part of the medial face and appears to be narrower anteriorly than posteriorly whereas in primulina the anterior part of the medial face is not scooped out but is moderately inflated and the bulla appears to be of uniform breadth anteriorly and posteriorly. By actual measurement the breadth of the bulla averages 59 per cent of its length in primulina but only 50 per cent in noveboracensis. Other respects in which the skull of the male of primulina differs from that of noveboracensis are as follows: Linear measurements of teeth more; relative to the basilar length, the length of the tooth-rows averages more, whereas the interorbital breadth and orbitonasal length are less.

When skulls of females are compared, each of the differences mentioned above is found to apply, except that the degree of difference is in some parts greater, for example, in the tympanic bullae. In primulina, the bulla is in general like that of the male noveboracensis, whereas in the female noveboracensis it is less inflated, especially anteromedially, shorter, relatively narrower, and in ventral view projects little or none below the squamosal floor of the braincase. The breadth of the bulla averages 51 per cent of its length in primulina but only 47 per cent in noveboracensis. The bullae project below the basioccipital on the average, for a distance of 2.9 millimeters in female primulina and only 2.3 millimeters in female noveboracensis. In primulina the temporal ridges are well developed and fuse to form a low sagittal crest, but in noveboracensis the ridges are absent. Also, in primulina the mastoid processes project farther laterally beyond the braincase. The skull of female noveboracensis is much lighter than that of primulina. Average weights of the two are 1.7 and 2.2 grams. The skulls of females of primulina and noveboracensis differ more than do the skulls of males.

Compared with the skull of spadix, that of the male, and the female, of primulina averages smaller in every part measured. Expressed in percentages of the basilar length, the two depth measurements of the skulls are not significantly different, but, excluding the measurements of the bullae and teeth, the other cranial measurements are less. The main difference in relative proportions is in the tympanic bullae which average only a half millimeter shorter in males of primulina and one and one-tenth millimeters shorter in females. The bullae are, therefore, relative to the basilar length, longer in primulina. The skull of primulina, then, differs from that of spadix mainly in smaller size and relatively longer tympanic bullae, especially in males.

Compared with the skull of M. f. longicauda, that of both sexes of primulina averages smaller in every part measured, except in males where the length of the tympanic bulla, and breadth and length of M1 are the same or slightly larger in primulina. Relative to the basilar length, the length of the tympanic bullae, and in females only, the depth measurements are greater in primulina but all the others, in both sexes, are less. These ratios reflect the relative narrowness of the skull of primulina. Upon direct comparison the narrowness is especially noticeable in the interorbital region, mastoid region, tympanic bullae, and across the zygomata.

Compared with the skull of M. f. neomexicana that of both sexes of primulina averages smaller in every part measured. Excepting the measurements of the teeth, most of the other measurements are constantly larger. Relative to the basilar length, the length of tooth-rows and length of tympanic bulla are more, but excepting the depth measurements, the others are less. Still other differences are, in primulina, less well-developed sagittal crest, anterolateral corner of bulla rounded rather than "square," and in males a transversely convex rather than flat interorbital region.

Compared with M. f. frenata and M. f. texensis, the skulls of males of primulina differ in being smaller in every part measured but relative to the basilar length, have longer tooth-rows, a lesser zygomatic breadth and are less constricted interorbitally.

Compared with the skull of M. f. olivacea, those of both sexes of primulina average smaller in every part measured, have shallower (dorsoventrally) tympanic bullae, a lower sagittal crest and slightly weaker postorbital processes on the frontals. Relative to the basilar length, the several cranial measurements are about the same.

Comparison of the skull with that of M. f. arthuri has been made in the account of that subspecies.

Remarks.—The first specimens of this race known to have been preserved in study collections are one in the United States National Museum, taken at Bridge, Carroll County, Missouri, many years ago by J. Burbage, and less than a dozen specimens preserved before 1900 from eastern Kansas in the University of Kansas Museum of Natural History. In 1913 Hartley H. T. Jackson bestowed a name on this animal on the basis of two specimens taken by him in southwestern Missouri. Later, through the efforts of Charles D. Bunker, and his associates at the University of Kansas, nearly 100 specimens were saved from eastern Kansas, principally from Douglas County. In the course of the present study, Lawrence V. Compton obtained a topotype for the California Museum of Vertebrate Zoölogy, and with the assistance of Mr. B. G. Roberts, a good series of specimens from Boone County, Arkansas, was preserved in the same museum. In the early years of the 20th Century, the late B. H. Bailey at Coe College, Iowa, collected specimens from that state. The specimens from these several sources suffice to give a relatively clear idea of the characters of this subspecies.

Mustela frenata primulina is closely related to M. f. noveboracensis, from which, on the average, it differs in the lighter color of the upper parts of the summer coat, in the more intense coloring of the underparts, and in certain cranial features pointed out above. In the southern part of its range, however, noveboracensis has the underparts only a little less intensely colored with yellow than primulina. Also, the skull of the one topotype from 7-1/2 miles southeast of Carthage, a subadult male in brown, winter pelage, is almost exactly intermediate between that of noveboracensis from Massachusetts and primulina of Douglas County, Kansas, and Boone County, Arkansas. M. f. primulina often has the underparts white in winter, as does this topotype which agrees with the average of noveboracensis in small size of teeth and narrowness across the mastoid processes and zygomatic arches. However, it agrees with primulina in shape and relative size of the rostrum. It is almost exactly intermediate in shape and width of the tympanic bullae.

Three other males, but no females, all in winter pelage, are available from eastern Missouri. Of the two from Silex, Lincoln County, one is nearer noveboracensis and the other nearer primulina on the basis of cranial characters. The third specimen, from four miles south of Lesterville, so far as I can determine by examination of individual cranial characters and tabulation of results, is exactly intermediate. Final decision on the proper allocation of specimens from the parts of Missouri represented can best be made when skulls of females are available. From the fact that the skull of the female referred to noveboracensis from Golconda, Illinois, shows almost as many characters of primulina as of noveboracensis, it is judged that females from as far west as Silex and Lesterville, Missouri, will show even more characters of primulina and so be referable to that form. If this supposition be correct, the present reference of the almost exactly intermediate males, from eastern Missouri, will stand; otherwise, it may not.