Part 26

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

=Mustela erminea alascensis= (Merriam)

Ermine

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

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

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

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

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

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

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

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

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

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