Type.—Obtained in the Pashimeroi Mountains, 9,700 ft., Custer County, Idaho, by C. H. [Merriam] and V. [Bailey] in 1890; type in United States National Museum.
Racial characters.—Similar to arvicoloides but slightly smaller and redder.
Measurements.—A female from Stay-a-while Spring, Columbia County, measures: total length 228; length of tail 73; hind foot 25; ear 14.
Distribution.—The Blue Mountains of southeastern Washington.
Microtus oregoni oregoni (Bachman)
Creeping mouse
Arvicola oregoni Bachman, Jour. Acad. Nat. Sci. Philadelphia, 8:60, 1839.
Microtus oregoni [Miller], N. Amer. Fauna, 12:9, July 23, 1896.
Microtus morosus [Elliot], Field Columb. Mus. Publ. 30, zoöl. ser., 1:227, February 1, 1899 (type from Boulder Lake, 5,000 ft., Clallam County, Washington).
Microtus oregoni oregoni [Miller], U. S. Nat. Mus. Bull., 79:227, December 31, 1912.