_Evotomys idahoensis_ Merriam, N. Amer. Fauna, 5:66, July 30, 1891. _Clethrionomys gapperi idahoensis_ Whitlow and Hall, Univ. California Publ. Zoöl., 40:265, September 30, 1933. _Type._--Obtained at Sawtooth (Alturas) Lake, 7,200 ft., Blaine County, Idaho, by C. H. Merriam and V. Bailey, on October 4, 1890; type in United States National Museum. _Racial characters._--Similar to _saturatus_ but brain case longer and narrower and dorsal area more reddish. _Measurements._--Seven males and 6 females from the Blue Mountains average, respectively: total length 138, 142; length of tail 41, 41; hind foot 18.7, 19.0; ear 13.6, 13.5; weight 20.5, 22.7 grams. _Distribution._--The Blue Mountains of southeastern Washington. =Clethrionomys gapperi cascadensis= Booth _Evotomys gapperi saturatus_ Taylor and Shaw, Occ. Pap. Chas. R. Conner Mus., no. 2:23, December, 1929. _Clethrionomys gapperi cascadensis_ Booth, Murrelet, 26:27, August 10, 1945. _Type._--Obtained 2 miles south of Blewett Pass, 3,000 ft. elevation, Kittitas County, Washington, by G. G. Cantwell, on October 30, 1921; type in United States National Museum. _Racial characters._--Dark and dull with underparts dull buffy. _Measurements._--Ten adults from the Cascade Mountains average (Booth, 1945: 27): total length 162; length of tail 50; hind foot 19; ear 14. _Distribution._--The Cascade Mountains, according to Booth (_loc. cit._, p. 28), from Hannegan Pass south to Mount Adams. Marginal localities listed are: Swamp Creek, Glacier Peak, McKenna, and Mt. St. Helens. These, and other localities listed by Booth are not plotted on the accompanying distribution map (fig. 111). =Clethrionomys gapperi nivarius= (Bailey) _Evotomys nivarius_ Bailey, Proc. Biol. Soc. Washington, 11:136, May 13, 1897. _Evotomys gapperi nivarius_ Taylor and Shaw, Occ. Papers Chas. R. Conner Mus., no. 2:23, 1929. _Clethrionomys nivarius_ Svihla, Murrelet, 12:54, May, 1931. _Type._--Obtained on the northwest slope of Mt. Ellinor, 4,000 ft. elevation, Mason County, Washington, by C. P. Streator, on July 9, 1894; type in United States National Museum. _Racial characters._--Similar to _saturatus_ but paler throughout. _Measurements._--Two males and a female from 1 mile northwest of Lake Cushman, Mason County, average: total length 140; length of tail 42; hind foot 18; ear 13. _Distribution._--The Olympic Mountains, from Sol Duc Hot Springs (W.S.M.) south and west at least to Staircase, on Lake Cushman (W.W.D.). =Clethrionomys californicus occidentalis= (Merriam) California red-backed mouse _Evotomys occidentalis_ Merriam, N. Amer. Fauna, 4:25, October 8, 1890.