Part 59

The skull (plate 40) is complete and unbroken. The teeth all are present and entire except right I^3 which has the anterior half broken away. The skin is complete, fairly well made, and in summer pelage.

Range.--Canadian and Hudsonian life-zones from near 56°N in the Rocky Mountains of British Columbia and Alberta and Ootsa Lake along the Fraser and Chilcotin rivers south to Alta Lake, in the Caribou and Monashee mountains, probably in the Selkirks and Rockies, and through the Rockies of Montana into extreme northern Wyoming. See figure 29 on page 221.

Characters for ready recognition.--Differs from M. f. longicauda by near (14 n) Brussels Brown rather than near (h) Clay Color of upper parts and in males by relatively shallower 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 59 per cent of the mastoid breadth; from M. f. nevadensis by greater average size, see measurements.

Description.--Size.--Male: Two adults from Florence, Montana, measure as follows: Total length, 440, 440; length of tail, 165, 161; length of hind foot, 47, 49. Corresponding measurements of an adult male from Quesnel, British Columbia, are: 443; 168; 55. Tail amounts to 60, 58, and 61 per cent as long as head and body. Length of hind foot averages more than basal length.

Female: The type specimen, the only typical adult or subadult specimen of this sex of which external measurements are available, measures: Total length, 392, length of tail, 150, length of hind foot, 46. Tail is 63 per cent as long as head and body. Length of hind foot amounts to more than basal length.

The differences in external measurements, between the one female and the average of the three males are: Total length, 49; length of tail, 15; length of hind foot, 4.

Externals.--Longest facial vibrissae brown or white (often both colors in same specimen) and extending beyond ear; carpal vibrissae same color as underparts and extending to or beyond apical pad of fifth digit; hairiness of foot-soles (in summer pelage) slightly less than shown in figure 19.

Color.--Upper parts, in summer, near (14 n) Brussels Brown, more blackish and less reddish than tone 4 of Burnt Umber of Oberthür and Dauthenay, pl. 304; in type near tone 4, pl. 301 of Oberthür and Dauthenay. Underparts, in summer, Buff Yellow or near (20 c) Amber Yellow. In winter, all white except tip of tail which is at all times black. Upper parts of uniform color except for occasional slight darkening of top of head and along mid-dorsal line of back. Color of underparts extends distally on posterior sides of forelegs over feet, on medial sides of hind limbs over antiplantar faces of toes and over proximal two-thirds of ventral side of tail. Least width of color of underparts amounting to 43 per cent of greatest width of color of upper parts, 75 per cent in male from 4 miles northeast of Quesnel, British Columbia, and 52 (33-66) in four males from Montana. Black tip of tail in four males from Montana averaging 50 (44-60) mm. long. Thus averaging approximately as long as hind foot and 33 per cent of length of tail-vertebrae.

Color not different than in many specimens of M. f. nevadensis. Color comparison with M. f. longicauda has been made in the account of that subspecies.

Skull and teeth.--Male (based on 5 adults and 2 subadults from British Columbia and 4 adults from Montana): See measurements and plates 16-18. As described in Mustela frenata longicauda except that: Weight, 5.0 (3.8-6.0) grams; basilar length, 46.7 (43.6-48.8); postorbital breadth in one of nine instances less than 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; breadth of rostrum less than length of tympanic bulla; anterior margin of tympanic bulla as far posterior to foramen ovale as width of 2-1/2 to 5 upper incisors; length of tympanic bulla not less than length of lower molar and premolar tooth-row and shorter than rostrum.

Female (based on the type, specimen): See measurements and plates 31-33, 40. As described in Mustela frenata longicauda except that: Weight, 3.5 grams; basilar length, 41.6 mm.; zygomatic breadth more than distance between anterior palatine foramen and anterior margin of tympanic bulla; postorbital breadth more than width of basioccipital measured from medial margin of one foramen lacerum posterior to its opposite; least width of palate more than outside length of P^{4}; tympanic bulla as far posterior to foramen ovale as width of 4-1/2 upper incisors; height of tympanic bulla less than distance from anterior margin of tympanic bulla to foramen ovale; length of tympanic bulla less than length of rostrum. If more than one skull were available of the female of oribasus it is believed that the description would agree with that of longicauda in nearly all features.

The skull of the female is 30 per cent lighter than that of the average male.

Comparison with longicauda reveals that, on the average, skulls of males are larger, relative to the basilar length broader across the mastoids, shallower through the braincase as measured at the anterior end of the basioccipital exclusive of the sagittal crest, with longer rostrum. Compared with nevadensis, the skull averages larger in all measurements taken, and has a relatively broader rostrum, relatively greater mastoid breadth and a braincase which is shallower relative to the basilar length. By weight, the skull of nevadensis is a fourth lighter, and in linear measurements 5 to 18 per cent smaller.

Remarks.--Some of the specimens from Montana, which here are referred to oribasus, more than half a century ago were listed by Coues (1877:138) under the name longicauda. It was not until 1899 that this race was given a name by Bangs, who at that time (1899B:81) accurately made out the distinctive color features. Distinctive cranial characters cannot be described with assurance even now because there still are too few specimens.

The type specimen, at one time examined by the present writer, has on the stuffed skin no well-developed mammae, scrotal pouch, or other visible sexual part. Probably the collector's sex mark for female is correct.

As judged by the two skulls of subadult males from the Barkerville region, individuals of this race attain larger size than do those of longicauda. On the basis of larger size than either longicauda or nevadensis, the specimens from the Rocky Mountains of Montana and two from northern Wyoming are referred to this race. The short, wide, flat, tympanic bullae, relatively great mastoidal breadth, and some other features of the specimen from Donovan, Montana, point toward oribasus, whereas nearly as many more cranial features, in this instance mainly differences in size, are indicative of nevadensis to which race the specimen might almost equally well be referred. Another male from Darby, in the Bitterroot Valley of Montana, has a slightly longer hind foot than those from Florence, but a female from Hamilton, agrees more nearly with nevadensis. The average of all the specimens from the Bitterroot Valley is a little nearer oribasus. Four skulls from Buffalo, Wyoming, here referred to nevadensis show approach to oribasus in size of skull. The specimens from Big Snowy Mountains, and the Highwood Mountains of Montana are too young clearly to show size of the adult skull, but are distinctly darker colored than longicauda of the plains country proper. Of two subadult females from Tacy, Montana, the color of the one in summer pelage is distinctly nearer that of oribasus and nevadensis than it is to that of longicauda to which some approach in color might be expected. The reduced size of both of the specimens is further suggestive of nevadensis and it may be that adult specimens from these more eastern mountainous areas in Montana will show that nevadensis is the name proper to apply to animals of this region.

Intergradation with nevadensis is suggested by specimens collected from along the upper reaches of Okanagan Lake, British Columbia, by Major Allan Brooks and Mr. J. A. Munro and by a series of skulls from Ione, Pend Orielle County, Washington, lent me by Mr. Walter Dalquest. At each place, the average of all specimens is nearest to that of nevadensis.

Specimens from near Waterton Lake show several steps in the transition from the light-colored longicauda type of coloration to the darker coloration characterizing oribasus. One taken here, at a time when the body of water referred to seems to have been known as Chief Mountain Lake, is barely dark enough to be placed with oribasus. Two other specimens from across the Canadian Border labeled as "Waterton Lake Park" are slightly lighter colored above, and on this account are placed with longicauda.

The two adult males from Lillooet, British Columbia, are referable to oribasus although neither is quite typical. One has a saturated coloration suggestive of that of altifrontalis and the skull is shorter and broader than in other specimens of oribasus. The female from Lillooet, skin alone, no. 916, Prov. Mus., B. C. is small for oribasus. The female, no. 1539, collection of Kenneth Racey, from Alta Lake, in brown winter pelage, in almost every measurement falls nearly midway between altifrontalis and oribasus but slightly nearer the latter. The skull from Chezacut and 3 animals from Wistaria, British Columbia, probably are females and show a greater average size than specimens from farther to the southeast. For example, the basilar length of the skull, 44.8 (44.3 to 45.1), exceeds that of the type specimen. The animals from Wistaria on Ootsa Lake furnish the northwesternmost station of occurrence of which I have record for this subspecies.

The northernmost records of occurrence, at "Clearwater River, Peace River, B. C," and at Little Prairie, are furnished by a white skin without skull, no. 257450, U. S. Nat. Mus., purchased on August 2, 1932, at the place mentioned by W. H. Sheldon and Richard Borden, and a skull with white winter skin, no. 3585, Provincial Museum, British Columbia, respectively. The characters distinguishing longicauda and oribasus are not shown by white winter skins; the skull shows some features of longicauda, and the reference of these specimens to oribasus rather than longicauda is tentative.

Only the skull from Little Prairie shows evidence of infestation of the frontal sinuses by parasites. In the Barkerville area of British Columbia, Mr. and Mrs. Thomas T. McCabe obtained only 2 skulls of this subspecies from a total of 238 weasel skulls gathered by local trappers. The others were Mustela erminea.

Specimens examined.--Total number, 46, listed by localities from north to south and unless otherwise indicated, in the United States National Museum.

=British Columbia.= West of Hudson Hope, 1; Clearwater River, tributary to Peace River, 1; Little Prairie, a few miles south of Peace River and about 40 miles west of the main highway between Dawson Creek and Fort St. John, 1; Wistaria, 3; Four Mile Creek, 4 mi. NE Quesnel, 1; Isaacs Lake, 3200 ft., 1; Barkerville region, 1; Clear River, 4800 ft., 1; Chezacut, 1; Lillooet 3 (2, 1); Alta Lake, 1; source of Kettle River, 7500 ft., 1; E side Beaverfoot Range, 4000 to 4500 ft. between Fraser Creek and 6 mi. SE of Fraser Creek, 1; Cranbrook, 1; head of Cross River, 10 mi. below Assiniboine Pass, 1; camp east of "Kootanie," 1; camp east of Kootanie River, 1.

=Alberta.= Thoral Creek, 7000 ft., 50 mi. NE Jasper, 1.

=Montana.= Glacier? County: Chief Mt. Lake (= Waterton Lake), 1. Flathead County: Columbia Falls, 1. Chouteau? County: Highwood Mts., 1. Fergus? County: Big Snowy Mts., 1. Wheatland County: Harlowton, 1. Ravalli County: Florence, 2; Hamilton, 1; Darby, 1; Carlos [= Charlos] Heights, 2; Tin Cup District, 2; no locality more definite than county, 2. Beaverhead County: Donovan, 1. Madison County: Sheridan, 1. Gallatin County: Ranch 7-11, Eldridge, 1. Stillwater County: Tacy, 2. County in question: Gallatin Valley, 1; Yellowstone Park, 1.

=Wyoming.= Glen Creek, Mammoth Hot Springs, 1. Park County: Four Bears, 1.

=Mustela frenata alleni= (Merriam)

Long-tailed Weasel