DISTRIBUTION AND SPECIATION

Weasels of the subgenusMustelaare known from the Pleistocene but not from deposits laid down at an earlier time (see page10). 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. ermineacame 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 rixosais 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 minutusn. 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 fromM. 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 ofMustela africanacould have been derived by a decrease in hairiness, although it would be necessary to suppose that the thenar pad has been retained inafricanaand has been lost in the livingerminea. The alternate possibility, namely, that the thenar pad was a relatively recent acquisition in theafricanaline seems less probable. The tail ofermineais of "average" length and in size of entire animalermineais intermediate between the other American weasels. Structurally,Mustela ermineaappears 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 ermineais 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 theermineastem 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. rixosais, in each instance, the most aberrant of all the weasels,Mustela nivalisof 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 whereermineaandrixosaoccur together,ermineais 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 rixosamay eat numbers of insects (see page176beyond),—a kind of food whichMustela ermineais 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,ermineabecomes almost as small asrixosaand 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 ofermineais to be found. In the Alleghenies of the eastern United States onlyrixosaoccurs. In New England whereermineaapproaches the size ofrixosa, 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 speciesermineainvaded the western United States and in the process of invasion probably developed there the small size appropriate to permitermineato live in that latitude before it could do the same thing in the Appalachian region. Later thanerminea, 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 whichermineawas of small size, but in the Appalachian region of the eastern United States continued on southward to the limits of temperature tolerant for it becauseermineahad 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 withfrenataas witherminea. It is true thatermineaandfrenataoccur 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, whereermineais of exceptionally small size. In these mountains and in the boreal mountainous parts of the intervening region of the United States,ermineaand the large-sizedfrenataoccur together over a wide area. Presumably the two occupy different ecologic niches, much asrixosaandfrenataprobably 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 inerminea.

Several subspecies ofMustela frenataoccur 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 withMustela frenata frenataof 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 offrenataall those subspecies offrenatawhich 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 speciesfrenata, 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 thefrenatastock 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 thefrenatastock 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 costaricensisandMustela frenata goldmanimay 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 ofM. frenatafrom 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 africanais 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 inM. africanaas it has in the other American weasels. Another primitive feature in the basicranial region ofM. africanais 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 thanMustela.

Some specializations are obvious inMustela 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 (subgenusMustela) 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.

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 betweenM. africanaand 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 holarcticMustela erminea, the species which is regarded as most closely resembling the stem form. Also, the mentioned characters in adults ofM. africanaresemble ontogenic stages passed through by other weasels. Consequently, it is thought thatM. africanacrossed the filter-barrier from North America to South America, remained isolated from the original stock for a length of time sufficient to permitafricanato differentiate from North American weasels andvice versato such a degree that crossbreeding with thefrenatastock was prevented whenfrenata, 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 whichermineais the most nearly direct descendant. Geographic and climatic changes may have operated to isolate, and then to foster morphologic differentiation of, firstrixosain Eurasia, nextafricana, third thetropicalissection ofM. frenata, and finallyM. frenataitself, leavingM. ermineaas a modern version, somewhat altered to be sure, of the stem form. Some of these ideas are expressed in figure16. 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. ermineain almost every one of its characteristics is generalized and potentially progressive whereasafricanaretains more characters which are truly primitive along with a few which are specializations.M. africanais potentially the least progressive of any of the American weasels. The most specialized weasels are the North American races ofMustela frenata. A progressive series of increasing specialization is comprised in (1)M. africana, (2) theM. tropicalis(Central American, lowland) section ofM. frenata, and (3) the races ofM. frenatain 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 page51.

Temperature seems not to be an important factor in directly limiting the distribution of weasels, sinceM. frenataoccurs from the hottest to some of the coldest parts of the Americas. DoM. ermineaandM. rixosarange 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 inM. ermineaand with increased size inM. 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. InMustela frenatathese 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 1and the description of color on page51may 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,panamensisandcostaricensisare 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 ofMustela 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 aPhyllotisin Perú and the weasel in Washington which needed nature's aid in catchingMicrotus.Mustela frenata goldmaniof the highlands of southern México, which is known to attack the huge pocket gophers,OrthogeomysandCratogeomys, has a weaker dental armature thanMustela frenata texensiswhich does not have to overcome prey so formidable as doesgoldmani. Equally formidable enemies endangerM. f. goldmaniandtexensis. 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 ofMustelahas 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 subspeciesMustela frenata nevadensisof 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. nevadensisintergrades in a relatively narrow belt with the lighter-colored, longer-tailed and cranially differentMustela frenata longicauda, which has a geographic range almost equally extensive.M. f. longicaudaalso 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 differentMustela frenata primulinaand 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 ofM. 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 ofM. f. longicaudaor for that matter from well within the geographic range ofM. 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 thatM. f. longicaudaand for that matterM. f. nevadensisandM. f. primulinawould lose their distinctive characteristics because of the crossbreeding that is every year going on betweenlongicaudaandnevadensison the one hand and betweenlongicaudaandprimulinaon the other hand.

Sumner (1932:84) suggests that homogeneity is prevented by population pressure. Applying his suggestion to the speciesMustela frenatawe could say that the subspecieslongicaudapressing westward meets strong pressure from the subspeciesnevadensispressing 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 producepartial discontinuitybetween 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 themodus operandiof 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.Mustelais 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 inMustelathere 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 inMustelacan 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 ofMustelaresult 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 AmericanMustela, 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 ofMustelaare 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 andcontinuouscontact 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.

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 thatMustela rixosaoccurred also in the Old World, and in 1943 I emphasized that a second American species,Mustela erminea, was circumpolar in distribution. In neitherrixosa, norerminea, 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. richardsoniiandM. 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 asPutorius ermineusof the Old World; the male that was brown in winter they designated by their earlier proposed nameP. fuscus, and the female they namedP. agilis. The ermine, subspeciesM. erminea cicognanii, they calledP. pusillus. Their fifth name,P. frenatus, included at least some animals that today are assigned to the subspeciesM. 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 namerichardsonii, 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 ofPutorius richardsoniifor the animal now known asM. 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 namerichardsonii. 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.

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 ofagilis(1844 and 1853) and ofamericana(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 namejavonicain 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 nameermineaby 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 1943ermineahas 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 toermineaprobably resulted in a composite use of the name in that one or another subspecies of the American speciesMustela frenatamay also have been included with individuals truly of the specieserminea.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 speciesnivalisare intermediate in size betweenMustela ermineaandMustela 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 toMustela erminea cicognaniibut also to females ofMustela frenata noveboracensis, and conceivably to both sexes ofMustela rixosaof 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 ofMustela 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 byMustela 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]vulgarisseems 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 ofMustela nivalisLinnaeus (1766). Probably the name as used by Ord was composite in the sense that he may have intended it to apply to females ofMustela frenata noveboracensisas well as to one or both sexes ofMustela erminea cicognaniiand, if he ever saw them, to the two sexes ofMustela 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 ofMustelanamed 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 spelledCigognaniiwas correctly spelled on page39. For a detailed consideration of this name see the account of the subspeciescicognaniion page120.1838.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 asM. e. arcticaand sometimes to part of the subspecies now designated asM. e. cicognaniiunder the principal treatment of which see (page120) for a detailed account of the basis of the namerichardsonii, and the reasons for regarding Fort Franklin as the type locality.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 tolongicauda. 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 ofMustela 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 anomen 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 namedM. e. cicognaniiseems to have included some individuals of the also earlier namedM. 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 namemundusfor the California weasel north of San Francisco Bay thus restricting the application of the namexanthogenys. 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 namedmunda.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 nameMustela agilisfor 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.1865.americana(Mustela ermineaVar. 3) Gray, Proc. Zoöl. Soc. London, 1865:111. The larger individuals of American weasels of bothMustela ermineaandMustela frenatafrom 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 byMustela americanaTurton (1806) the name for the American marten.1865.americana(Mustela vulgarisVar.) 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 anomen nudumbut 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 namelongicauda. See the account oflongicaudafor a more detailed account of the nameculbertsoni.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 namedmacrura.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 toalascensis.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.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 ofnoveboracensis.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,occisorwas ordinarily used as the name of a full species but since then has been arranged as a subspecific name underMustela 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 ofrichardsonii.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 nameaudaxuntil 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,audaxis a synonym ofPutorius 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 fromrichardsoniiwhich has priority.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 ofmuricuswith 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.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 ofsempleiwhich 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 tolongicaudaand from 1891 until 1936 toarizonensis.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 namearizonensis.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,xanthogenyswas 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 namexanthogenys.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 subspeciesfrenata.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.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.

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 nameermineaby 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 1943ermineahas 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 toermineaprobably resulted in a composite use of the name in that one or another subspecies of the American speciesMustela frenatamay also have been included with individuals truly of the specieserminea.

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 speciesnivalisare intermediate in size betweenMustela ermineaandMustela 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 toMustela erminea cicognaniibut also to females ofMustela frenata noveboracensis, and conceivably to both sexes ofMustela rixosaof 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 ofMustela 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 byMustela 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]vulgarisseems 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 ofMustela nivalisLinnaeus (1766). Probably the name as used by Ord was composite in the sense that he may have intended it to apply to females ofMustela frenata noveboracensisas well as to one or both sexes ofMustela erminea cicognaniiand, if he ever saw them, to the two sexes ofMustela 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 ofMustelanamed 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 spelledCigognaniiwas correctly spelled on page39. For a detailed consideration of this name see the account of the subspeciescicognaniion page120.

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 asM. e. arcticaand sometimes to part of the subspecies now designated asM. e. cicognaniiunder the principal treatment of which see (page120) for a detailed account of the basis of the namerichardsonii, and the reasons for regarding Fort Franklin as the type locality.

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 tolongicauda. 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 ofMustela 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 anomen 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 namedM. e. cicognaniiseems to have included some individuals of the also earlier namedM. 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 namemundusfor the California weasel north of San Francisco Bay thus restricting the application of the namexanthogenys. 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 namedmunda.

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 nameMustela agilisfor 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.

1865.americana(Mustela ermineaVar. 3) Gray, Proc. Zoöl. Soc. London, 1865:111. The larger individuals of American weasels of bothMustela ermineaandMustela frenatafrom 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 byMustela americanaTurton (1806) the name for the American marten.

1865.americana(Mustela vulgarisVar.) 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 anomen nudumbut 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 namelongicauda. See the account oflongicaudafor a more detailed account of the nameculbertsoni.

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 namedmacrura.

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 toalascensis.

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.

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 ofnoveboracensis.

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,occisorwas ordinarily used as the name of a full species but since then has been arranged as a subspecific name underMustela 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 ofrichardsonii.

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 nameaudaxuntil 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,audaxis a synonym ofPutorius 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 fromrichardsoniiwhich has priority.

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 ofmuricuswith 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.

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 ofsempleiwhich 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 tolongicaudaand from 1891 until 1936 toarizonensis.

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 namearizonensis.

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,xanthogenyswas 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 namexanthogenys.

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 subspeciesfrenata.

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.

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 (subgenusMustelaproper) 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 subgenusMustela. 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.

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