The gestation period of _Mustela f. nevadensis_ has been recorded as more than 131 days (Hall, 1938B: 250). The gestation period of the long-tailed weasel of eastern United States has been recorded as more than 70 days. Three to five young are born in a litter, usually four. =Mustela frenata nevadensis= Hall _Mustela arizonensis_ Taylor and Shaw, Occ. Pap. Chas. R. Conner Mus., no. 2:11, December, 1929. _Mustela washingtoni_ Taylor and Shaw, in part, Occ. Pap. Chas. R. Conner Mus., no. 2:11, December, 1929. _Mustela frenata nevadensis_ Hall, Carnegie Inst. Washington, Publ. 473:91, November 20, 1936. _Type._--Obtained 3 miles east of Baker, White Pine County, Nevada, by E. R. Hall and W. C. Russell on May 30, 1929; type in Museum of Vertebrate Zoölogy. _Racial characters._--Size medium; colors pale; back near Brussels Brown in summer, chin white and underparts yellow, rarely orange; color in winter white with black tip on tail. _Measurements._--A male from Neppel, Grant County, measures: total length 412; length of tail 151; hind foot 43; ear 19. Two males from Yakima, Yakima County, average: 379; 135; 42.5; 21; weight 176.5. A female from Ellensburg and one from 4 miles east of Ellensburg, Kittitas County, average: 284; 98; 33; 17. _Distribution._--From the high Cascades eastward, save for the Blue Mountains area. Marginal occurrences are Barron (Hall, 1936: 93) and Easton (W. W. D.). _Remarks._--Specimens from the northern Cascades are intergrades between _nevadensis_ and the form to the west, _altifrontalis_. Specimens from extreme northeastern Washington might be referred to _oribasa_ Bangs as readily as to _nevadensis_. =Mustela frenata effera= Hall _Mustela frenata effera_ Hall, Carnegie Inst. Washington, Publ. 473:93, November 20, 1936. _Type._--Obtained at Ironside, Malheur County, Oregon, by H. E. Anthony on September 8, 1912; type in American Museum of Natural History. _Racial characters._--Similar to _nevadensis_ in color but smaller, with smaller, lighter skull. Color in winter white with black tip on tail. _Measurements._--A female from Prescott, Walla Walla County, measures: total length 310; length of tail 105; hind foot 34. _Distribution._--Southeastern Washington, south of the Snake River. Specimens from Walla Walla and Prescott have been examined. =Mustela frenata washingtoni= (Merriam) _Putorius washingtoni_ Merriam, N. Amer. Fauna, 11:18, June 30, 1896. _Mustela washingtoni_ Miller, U. S. Nat. Mus. Bull., 79:98, December 31, 1912. _Mustela frenata washingtoni_ Hall, Carnegie Inst. Washington, Publ. 473:106, November 20, 1936.