In comparison with streatori, skulls of males and females average smaller in every cranial measurement taken. Teeth of about same size and males 9 per cent, and females 8 per cent, lighter. In relation to basilar length, skull of female shallower, tympanic bullae slightly shorter and, on the average, zygomata less expanded.
In comparison with muricus, males average larger in every measurement taken; 23 per cent heavier; in relation to other dimensions, braincase shallower at anterior end of basioccipital. Females are of about equal size; in relation to other dimensions, braincase shallower and mastoid and zygomatic breadths less.
Comparisons with invicta and fallenda have been made in the accounts of those subspecies.
Remarks.—This is not a strongly marked race and in most of the characters used for differentiating it from other races it resembles either streatori to the west or muricus to the southeast. Nevertheless, there is a geographic area, the southern Cascades of Washington, throughout which individual characters are combined in essentially the same way and there are a few features, for instance, smaller skull of the female, in which gulosa differs from either of its close relatives. In view of these circumstances and because the animals can not well be included in the subspecies streatori or muricus, gulosa is recognized as distinct. The races gulosa and olympica are what might be termed weakly differentiated subspecies in contrast to the strongly differentiated subspecies streatori and muricus.
Of the 21 specimens in winter pelage, 17 are white and four are brown. The brown winter coat is distinctly paler, with more of a smoky tinge, than the brown summer pelage. The light-colored underparts are narrower than in the subspecies immediately to the east but are wider than in the coastal forms to the west. The dark color of the upper parts extends onto the chest in front of the forelegs, as in the coastal forms, in only one of the 13 specimens in summer pelage and in it on one side only. The black tip of the tail is short as in the coastal forms. One specimen is in transitional pelage. It has acquired approximately half of the white winter pelage and was taken on October 12, 1897, at Keechelus Lake.
Specimens examined.—Total number, 38, arranged by counties from north to south. Unless otherwise indicated, specimens are in the U. S. National Museum.
Washington. King County: 2 mi. E Skykomish, 2[51]. Kittitas County: Keechelus Lake, 3 (1[1]); Martin, 1[1]; Easton, 3. Pierce County: James Lake, 4370 ft., Mt. Rainier, 1; Glacier Basin, 5935 ft., Mt. Rainier, 1; Meslers Ranch, 2000 ft., 1 mi. W Rainier Park, 1. Lewis County: Mt. Rainier Nat'l Park, 5 (1 each from: Paradise Park, 5400 ft.; Reflection Lakes, 4900 ft.; Ohanapecosh [Hot] Springs, 2000 ft.; Tahoma Creek, 1[72]; Bear Prairie); also in Mt. Rainier Nat'l Park, Longmire, 3 (1[72], 1[94]). Skamania County: Mt. St. Helens, 6000 ft., 1. Klickitat County: Trout Lake, 18.
Mustela erminea muricus (Bangs)
Ermine