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

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

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

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

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

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

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

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

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

Mustela erminea alascensis (Merriam)

Ermine

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

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

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

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