Part 30

_Characters for ready recognition._--Differs from _M. f. noveboracensis_ and _M. f. primulina_ in that specimens of all ages have least width of color of underparts amounting to more than 41 per cent of greatest width of color of upper parts, and have light color of underparts extended onto hind foot rather than stopped short of ankle; adults with hind feet more than 50 in males and 40 in females; orbitonasal length more than 15.5 in males and 13.5 in females; length of tooth-rows more than 18.0 in males and 15.7 in females; mastoid breadth more than 25.5 in males and 22.0 in females. From _M. f. longicauda_ by color darker than near (_h_) Clay Color, in males by a flattened occiput in which the depth of the skull, exclusive of the sagittal crest and taken at the anterior border of the basioccipital, amounts to less than 58 per cent of the mastoid breadth.

_Description._--_Size._--Male: Three adults from Elk River, Minnesota, yield average and extreme measurements as follows: Total length, 458 (444-467); length of tail, 154 (140-165); length of hind foot, 55 (52-59). Tail averages 51 per cent as long as head and body. Length of hind foot averages more than basal length. Corresponding measurements of three subadults from Madison, Minnesota, are as follows: 453 (438-469); 157 (152-165); 50 (47-51). Tail averages 53 per cent as long as head and body.

Female: Three adults from Elk River, Minnesota, yield average and extreme measurements as follows: Total length, 387 (380-391); length of tail, 131 (121-138); length of hind foot, 44 (43-46). Tail averages 51 per cent as long as head and body. Length of hind foot more or less than (approximately equal to) basal length. Corresponding measurements of two adults and one subadult from Madison, Minnesota, are as follows: 385 (379-396); 137 (119-159); 42 (38-44). Tail averages 55 per cent as long as head and body.

The average differences in external measurements of the two sexes from Elk River, are: Total length, 71; length of tail, 23; length of hind foot, 11. At Madison, corresponding differences are 68, 20, and 8. Two adult females from Elk River, Minnesota, weigh 205 and 210 grams.

_Externals._--Longest facial vibrissae black, brown, or white (often all three colors in same specimen) and extending beyond ear; carpal vibrissae same color as underparts and extending to apical pad of fifth digit; hairiness of foot-soles (in summer pelage) as shown in figure 19.

_Color._--Winter pelage all white except tip of tail. In southern part of range sometimes assumes a brown winter coat. Summer pelage with upper parts ranging from near (16´) Cinnamon Brown to Vandyke Brown. Chin and upper lips white. Remainder of underparts ranging from near (a) Olive Ocher to Ochraceous Buff and Pale Orange Yellow. Tip of tail at all times black. Upper parts of uniform color except for occasional slight darkening of nose. Color of underparts extends distally on posterior sides of forelegs over toes onto antipalmar faces of feet and ankles, on medial sides of hind limbs to ankle, over antiplantar faces of toes and distomedial fourth of each tarsus, and over proximal fifth to third of under side of tail. Least width of color of underparts averaging (in 3 specimens from Elk River) 54 (47-59) per cent of greatest width of color of upper parts. Black tip of tail averaging same length as hind foot and 28 per cent of length of tail-vertebrae. Save for the greater width of the light-colored underparts and relatively short black tip of the tail, both features of _M. f. longicauda_, _spadix_ is variously intermediate, depending on locality, as between _noveboracensis_ and _longicauda_.

_Skull and teeth._--Male (based on 3 adults from Elk River, Minn.): See measurements and plates 16-18. As described in _Mustela frenata longicauda_ except that: Weight, 5.6 (5.0-6.5); basilar length, 49.0 (48.7-49.2); zygomatic breadth sometimes less than distance between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth more or less (about equal to) width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; interorbital breadth more or less than distance between foramen opticum and anterior margin of tympanic bulla; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 4 to 5 upper incisors; height of tympanic bulla more or less than distance from its anterior margin to foramen ovale; length of tympanic bulla less than length of rostrum; anterior margin of masseteric fossa below talonid of m1.

Female (based on 4 adults from Elk River, Minn.): See measurements and plates 31-33. As described in _Mustela frenata longicauda_ except that: Weight, 3.5 (3.3-4.0) grams; basilar length, 42.9 (42.3-43.2); least width of palate more or less than greatest length of P4; tympanic bulla as far posterior to foramen ovale as width of 3 to 5 upper incisors.

The skull of the female averages 33 per cent lighter than that of the male.

Skulls of adult males of _spadix_ from Elk River, Minnesota, as compared with those of _longicauda_ from Alberta, are larger in every part measured. Relative to the basilar length these skulls of _spadix_ are broader across the mastoid region, narrower across the zygomata, deeper through the plane of the postorbital processes, shallower through the braincase and have relatively shorter tympanic bullae. Whereas the tympanic bullae of _longicauda_ are, on the average, approximately as long as the rostrum (orbitonasal length), in _spadix_ the rostrum is longer than the bulla. Viewed posteriorly, the braincase of _spadix_ is seen to be much shallower and wider than that of _longicauda_. Indeed, the depth of the braincase, measured at the anterior end of the basioccipital, amounts to only 56 per cent of the mastoid breadth in _spadix_ as against 61 per cent in _longicauda_. The longer, waistlike, postorbital constriction, relatively smaller braincase, and especially the relatively narrower zygomatic expanse in _spadix_ imparts to its skull a more slender appearance than has the skull of _longicauda_. These differences are not shown by the skulls of females. To be sure, _spadix_, in most of its cranial measurements, averages slightly larger, has a relatively shallower braincase and is relatively deeper through the postorbital processes, but these differences are so slight that inclusion of one more specimen, of slightly different proportions, in the average might cause the average measurements to read as they do in _longicauda_.

Compared with _noveboracensis_, from Massachusetts, adult skulls of _spadix_, taking sex into account, are larger in every part measured and are relatively as well as actually wider and deeper throughout. Also, in _spadix_: Sagittal and lambdoidal crests higher, especially in females; anterior margin of tympanic bulla projecting up sharply from squamosal; occiput more flattened in posterior view; tooth-rows relatively and actually longer but orbitonasal length relatively shorter; postorbital processes more robust; zygomatic arches widely bowed outward rather than evenly rounded; canines larger; squamosal less swollen ventrally, especially in females. Between _noveboracensis_ and _spadix_, the differential cranial characters are greater in number and degree between females than between males. Comparison of the skull with that of _M. f. primulina_ is made in discussion of that subspecies.

_Remarks._--Edgar A. Mearns in 1889 and the early nineties took several specimens of this weasel and it was principally on these that Bangs in 1896 (p. 8) based his description. The best material, however, is that from Elk River, Minnesota, collected in later years by Bernard Bailey, and supplemented by one specimen taken in 1885 by Vernon Bailey and another by his sister Anna Bailey in 1891 at the same place.

_Mustela frenata spadix_ has just one structural feature of a "unique" kind which serves to differentiate it from the geographically adjoining subspecies. This feature is large size. The other diagnostic characters ascribed to _spadix_ are of an intermediate sort--intermediate as between two extremes, one found to the westward in _longicauda_ and the other to the eastward in _noveboracensis_. For example, the dark-colored upper parts are merely darker than in _longicauda_ and merely lighter than in _noveboracensis_. The color is not "different"; it is only "intermediate." Furthermore, each of the characters ascribed to _spadix_, including large size itself, undergoes change from one part of its geographic range to another; the characters are not constant over a wide area. Indeed, excepting the large size which remains relatively uniform over the northern two-thirds of the range, no two localities have been found from which the specimens can be said really to agree in characters.

By way of illustration, the coloration of the upper parts may be cited. Near the range of _noveboracensis_ the average coloration of individuals from one locality is only a little lighter than in _noveboracensis_. Farther westward the average coloration is a little lighter and farther westward yet, toward the range of the extremely light colored _longicauda_, the average coloration is lighter still. Although all these animals are darker than _longicauda_ and lighter than _noveboracensis_, those from the three places do not agree among themselves. Because of the lack of more than one character of a "unique" kind and because of the inconstancy, geographically, of other characters, and for that matter, lack of constancy geographically in combination of characters, the writer regards _spadix_ as a barely recognizable subspecies.

Examination of the specimens of _spadix_ shows that the individual variation in a single species is greater in a region of intergradation than it is some distance inside the borders of the geographic range of a well-marked subspecies. This is illustrated by three specimens of _M. f. spadix_ in fresh summer pelage from the single locality, Elk River, Minnesota. In these, the color of the upper parts varies from a little darker than Cinnamon Brown to Vandyke Brown. At any one locality well within the range of _longicauda_, or _noveboracensis_, there is nowhere nearly so much variation in color, even in much larger series of specimens.

Study of the specimens here assigned to _spadix_ reveals that some features regarded as of diagnostic value for one or the other of the two races, _longicauda_ and _noveboracensis_, behave differently. For example, the dark coloration of the upper parts, which is characteristic of _noveboracensis_, manifests itself far westward within the range of _spadix_ whereas the wider extent of the light-colored underparts, which is characteristic of _longicauda_, and the Olive Ocher, rather than Pale Orange Yellow, color of these underparts, are seen in varying degree all the way across the range of _spadix_. Thus, these animals are colored above like _noveboracensis_ and below like _longicauda_, but not _vice versa_. In these animals, then, the _longicauda_ type of underparts is dominant, in one sense of the word, over the _noveboracensis_ type of underparts, and the _noveboracensis_ type of upper parts is dominant over the _longicauda_ type of upper parts. Each of these features is subject to actual intergradation and does not always behave as a "unit character," that is to say, one which is either present or absent. However, the _noveboracensis_ type of upper parts is carried much farther west before being diluted than is the _noveboracensis_ type of underparts. Indeed, within the range of _noveboracensis_ itself, the broad extent of the _longicauda_ type of underparts is manifest. This is, of course, near the western margin of the range of _noveboracensis_.

The large size of males of _spadix_, as exemplified by specimens from Elk River (see measurements on p. 421), seems to be retained across the northern part of the range here assigned to the subspecies. This larger size than is found in _longicauda_ from Alberta, is shown also by some specimens from eastern North Dakota which are assigned to _longicauda_. However, the average of these Dakotan specimens, all characters considered, is nearer to my concept of _longicauda_.

Inspection of the cranial measurements of _spadix_ shows also that in addition to its large size it is distinguishable from any one of the geographically adjoining races by its relatively (to basilar length) greater, as well as actually greater, mastoidal breadth. This might be included with size as a unique character distinguishing _spadix_ from _longicauda_ and _noveboracensis_. However, it is not clear whether or not this greater mastoidal breadth is more than a function of the large size.

Excepting the greater mastoidal breadth and generally larger size of the skull, the cranial features distinguishing males of _spadix_ from _longicauda_ are features in which _spadix_ shows approach to _noveboracensis_. This is true, in _spadix_, of the relatively longer (in comparison with _longicauda_) rostrum, relatively lesser zygomatic breadth, relatively shallower braincase measured at the anterior end of the basioccipital, and relatively deeper skull as measured at the posterior borders of the last upper molars. This same approach to _noveboracensis_ already has been pointed out with respect to color of the upper parts and is evident also in the relative shortness of the tail which averages only 51 per cent of the length of the head and body rather than 55 per cent as in _longicauda_.

Because the _longicauda_ type of animal previously has been regarded as specifically distinct from the _noveboracensis_ type of animal, comment is offered below on selected specimens, referred to _spadix_, which are regarded as intergrades with _noveboracensis_ or with other subspecies.

No. 8722, Univ. Wisconsin, adult male, in the white winter coat, from north central Itasca County, Minnesota, obviously has characters of _M. f. spadix_ or _longicauda_ that occur to the west and _M. f. noveboracensis_ of the east. Selected outstanding characters of _longicauda_ are its long tail, anteriorly truncate tympanic bullae and large teeth. Characters indicating its affinities with _noveboracensis_ are smaller size of skull, general narrowness of skull, and relatively low tympanic bullae. The skull is intermediate as regards several individual structural features. For example, although long and narrow and in this feature more nearly approaching _noveboracensis_, the skull is wider than usual in that subspecies and thus approaches that of _longicauda_ or _spadix_. The hind foot, in the dried state, measures 47 millimeters. This large hind foot, obviously long tail (the specimen lacks external measurements), and anteriorly truncate bullae constitute basis for here referring the specimen to _spadix_. However, the seemingly small size of the body and the narrow skull clearly show relationship to _noveboracensis_.

Specimens, referred to _spadix_, from northern Iowa, are instructive as showing what happens where the ranges of _noveboracensis_, _primulina_, _spadix_, and perhaps _longicauda_, meet. No. 47167, Univ. Mich. Mus. Zoöl., a nearly adult female, taken on November 22, 1915, at Island, Clay County, and in process of assuming a brown winter pelage, retains enough of the dark summer pelage to show that the color was slightly lighter than average for _spadix_. The color pattern, white lips, and extension of light color of the underparts onto the feet, agrees with _spadix_ or _longicauda_ as does also the long tooth-row. The overall length of the skull is intermediate between that of _spadix_ and _primulina_. The proportions of the anterior part of the skull and of the tympanic bullae resemble those found in _primulina_. A subadult male skull only, no. 123846, American Museum of Natural History, from Webb, Clay County, shows approach to _primulina_ in the narrowness of the rostrum.

A young male from Ruthven, Iowa, no. 48340, Univ. Michigan, has a large skull approaching in size that of _spadix_, has the _longicauda-spadix_ type of light-colored underparts and color pattern, and is slightly darker above than true _longicauda_. Another subadult male in the white winter coat from Palo Alto County, no. 35756, Univ. Michigan, has a large skull, which shows approach to _primulina_ in its narrowness anteriorly and in some other features. Although the tail is of moderate length, the body is large as in _spadix_ or _longicauda_, and the length of the hind foot suggests _spadix_ or _longicauda_.

A subadult male, no. 425a, Iowa State College, from Manson, Iowa, in brown winter pelage, agrees with _primulina_ in the restriction of the area of the light color of the underparts and in less expanded zygomatic arches. The teeth are intermediate in size between those of _noveboracensis_ and _primulina_ on the one hand and those of _spadix_ and _longicauda_ on the other. In other respects it agrees with, or is more nearly like, _spadix_.

An adult female, no. 426a, Iowa State College, from Barnum, in the brown winter coat, agrees with _primulina_ except that the orbitonasal length of the skull is more as in _spadix_ and the presence of some light color on the lower part of the hind legs suggests _spadix_. The skull only, no. 440a, Iowa State College, labeled merely Webster County, Iowa, is almost a duplicate of no. 426a. A subadult male, no. 427a, Iowa State College, from Moorland, Iowa, only about six miles southeast of Barnum, likewise is indistinguishable from _primulina_ except for having a white winter coat and in being relatively broad in the mastoidal region. Nevertheless, both of these animals are here referred to _spadix_ because the average of specimens from this general area is nearer that of _spadix_. No. 497a, Iowa State College, an adult female in white winter pelage, from Ames, approaches _primulina_ in the narrow rostrum and smaller teeth but otherwise approaches or even agrees with _spadix_.

Two adult males, without external measurements, from Pilot Mound, Iowa, have skulls quite like males of _longicauda_ from Alberta. The only approach noted to eastern forms is the restricted color of the underparts on no. 2856, Coe College, which has a brown winter coat. The color of the underparts is not extended so far out on the feet as in _longicauda_. Also the tympanic bullae of this specimen are a trifle narrower. The other male, no. 2652, is in the white winter coat. The one female from the same place, no. 2660, Coe College, in brown winter pelage, has a skull notably unlike that of _longicauda_ or _spadix_; the skull is narrower and practically indistinguishable from that of the largest female skull of _primulina_ available from Lawrence, Kansas, save that the tooth-row is much longer. The color pattern also agrees with that of _primulina_ or _noveboracensis_ in that the color of the underparts extends only as far as the knee on the hind legs and is narrow on the belly. Nevertheless, another adult female, no. 120a from Amaqua Township, some 6 miles southwest of Pilot Mound, is in all respects typical of _spadix_. This is the more remarkable because another comparable specimen from less than 20 miles to the southwest in Worth Township is equally typical of _primulina_.

Two young females from Chester, Iowa, nos. 2656 and 2874/2873, Coe College, have skulls larger than those of corresponding age of _primulina_ or _noveboracensis_. The color is as in spadix. The color pattern of the underparts also is as in _spadix_ or _longicauda_ except that the width of the area of light color on the belly is restricted somewhat although not so much as in _noveboracensis_ or _primulina_. Of four males from the same place, also in the collection of Coe College, no. A2874 is a white skin only and does not provide diagnostic characters. The three other males, each in summer pelage, are marked and colored as are the two females from the same place except that male no. 2861 has the color of the underparts so much attenuated on the hind legs that it barely, uninterruptedly, extends to the feet. No. 2658 is young, or perhaps barely subadult. The skull is large and referable to _spadix_. The two adults, nos. 2861 and 2657, differ cranially from typical (Elk River, Minn.) _spadix_ only in being slightly narrower across the mastoids and in having the bullae a little narrower. In these departures they show some approach to _primulina_ and to _noveboracensis_. Another male, subadult, no. 2867, Coe College, from Decorah, which has acquired half of the white winter coat, agrees with the males from Chester except that the preorbital part of the skull is shortened much as in some specimens of _primulina_.

From Lansing, in extreme northeastern Iowa, a large subadult male, no. 2864, Coe College, of 453 mm. in total length and half through with acquiring the white winter coat, agrees with the males previously described from Chester except in having the palate narrower as in _noveboracensis_. The adult female available from Lansing, no. 2863/2862, Coe College, in white winter pelage except for the top of the head, although a large skin, has a skull smaller than that of any _spadix_ or _longicauda_ and of about the same size as that of no. 3838, Univ. Kansas Mus. Nat. Hist., of _primulina_, from Lawrence, Kansas, except that the skull of no. 2863/2862 is much narrower across the mastoids. This specimen, then, shows approach to _noveboracensis_ in narrowness of the mastoidal region, to _primulina_ in other respects and to _spadix_.

Many of these instructive specimens from Iowa, made available to the present writer by Mr. W. F. Kubichek, were brought together at the Coe College Museum by the late B. H. Bailey. Most of them were obtained from trappers who did not supply the conventional external measurements taken in the flesh. Even though these are lacking, the specimens clearly show that actual intergradation occurs where the ranges of _M. f. longicauda_, _spadix_, _noveboracensis_ and _primulina_ meet.

The dark color of the upper parts, restriction of the color of the underparts on the ankles with the result that the color reaches the toes in interrupted fashion, and large skull, of no. 18912 of the Museum of the University of South Dakota, from Roberts County, South Dakota, clearly place this specimen with _spadix_, rather than with _longicauda_. Likewise, male, subadult, no. 11376, Univ. South Dakota, from Clay County, South Dakota, is referable to _spadix_. Although without external measurements, the specimen obviously is large. The patch of summer pelage on its head and neck is darker than the summer pelage of _longicauda_, and the orbitonasal length is greater than the length of the tympanic bullae; all these features are characters of _spadix_. The adult male from Fort Sisseton, South Dakota, no. 188407, United States National Museum, figured by Merriam (1896, p. 20, figs. 7-9), is almost exactly intermediate between _longicauda_ and _spadix_, although here referred to the latter.