Two males, nos. 204883, adult, and 204884, young, from Sisters, Oregon, near the eastern base of the Cascades, show approach structurally to _M. f. washingtoni_ as it is represented at the nearby locality, Permilia Lake, at the west base of Mount Jefferson. Everything considered, however, the two specimens from Sisters are nearer to _effera_. A male from Condon, Oregon, shows approach to the Cascade race in slightly increased size. No perfect skulls of adult females are available from the part of northwestern Oregon in which _effera_ reaches its typical state of development as judged by the small size of the skull of the adult male. Skulls of adult females are available, however, from more nearly marginal localities. These, though smaller than in _nevadensis_, show relatively less difference in size when compared with _nevadensis_ than do skulls of males. Even so the females at these marginal localities are smaller than those of _nevadensis_ of comparable age and adequate material of adult female _effera_ from the region where the males attain their extreme of small size probably will show about the same relative difference in size between _nevadensis_ and _effera_ as is known to exist between the adult males of these two subspecies. The small size of a subadult female, no 74631, U. S. Nat. Mus., from Asotin, Washington, constitutes partial basis for this opinion. Of 14 adults examined none showed malformation of the frontal sinuses due to infestation by parasites. _Specimens examined._--Total number, 53, arranged within each state by counties from north to south. Unless otherwise indicated specimens are in the collection of the United States National Museum. =Oregon.= _Wasco County_: 4 mi. S The Dalles, 1[74]; Wapinita, 1; Antelope, 2; 7 mi. E Antelope, 5. _Gilliam County_: Condon, 1[46]. _Morrow County_: 10 mi. S Hardman, 1. _Umatilla County_: Umatilla, 2; 15 mi. E Ukiah, 4000 ft., 1[49]. _Union County_: Elgin, 1; 20 mi. E Lehman, 1[46]. _Wallowa County_: Horse Creek, 15 mi. N Paradise, 1; Enterprise, 1[46]; Wallowa Lake, 1[46]; Wallowa Mts., 8300 ft., 1. _Baker County_: Haines, 1[49]; Anthony, 3[2]; Bourne, 2. _Grant County_: Long Creek, 1[46]; Canyon Creek, 1[46]; Strawberry Mts., 2; Silvies, 1[14]. _Crook County_: Prineville, 4. _Deschutes County_: Sisters, 2; Bend, 1. _Lake County_: 3 mi. W Stauffer, 1; Fort Rock, 1[46]. _Harney County_: 25 mi. NW Burns, 1. _Malheur County_: 4000 ft., Ironside, 2[2]; 1-1/2 mi. S Vale, 2. =Washington.= _Walla Walla County_: Prescott, 4 (2[76], 1[60], 1[74]); Ft. Walla Walla, 2 (1[75]); Wallula, 1[76]. _Asotin County_: Asotin, 1. =Mustela frenata washingtoni= (Merriam) Long-tailed Weasel Plates 19, 20, 21, 34, 35 and 36 _Putorius washingtoni_ Merriam, N. Amer. Fauna, 11:18, pl. 4, figs. 3, 3a, 4, 4a, June 30, 1896.