Type.—Female, adult, skull and skin, No. 20050 Mus. Nat. Hist., Univ. Kansas; from 3 mi. NW Sundance, 5900 ft., Crook County, Wyoming; obtained on July 4, 1947, by H. W. Setzer; original No. 1692.

Range.—Bear Lodge Mountains in northeastern Wyoming and the Black Hills of South Dakota.

Diagnosis.—Size large (see measurements); general tone of upper parts drab; sides Ochraceous Buff (capitalized terms are of Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912); lateral stripes Fuscus Black washed with Ochraceous Tawny; ventral side of tail near (14' h) Ochraceous Orange and fringed with black.

Comparisons.—From Eutamias minimus pallidus (specimens from Buffalo in Johnson County, Ivy Creek, Rockypoint, Middle Butte, and South Butte in Campbell County, all in Wyoming, and Harrison, Sioux County, Nebraska), the subspecies to the southward, westward, and northward, E. m. silvaticus differs in: General tone of upper parts markedly darker, more reddish and less grayish; dorsal stripes darker; crown markedly darker. External measurements, and measurements and characters of the skull of the two subspecies, do not differ significantly. Unless otherwise specified all comparative material is in the Museum of Natural History of the University of Kansas.

From Eutamias minimus cacodemus (topotypes in the United States National Museum), the subspecies to the southeastward, E. m. silvaticus differs in the same manner in which it differs from E. m. pallidus, but the degree of difference is greater because E. m. cacodemus is even paler than E. m. pallidus.

From Eutamias minimus confinis (specimens from 17½ mi. E and 4½ mi. S Shell, 8500 ft., Big Horn County, Wyoming), E. m. silvaticus differs in: General tone of upper parts darker, more reddish and less grayish; sides of rump more reddish and less grayish; underside of tail more tawny; skull distinctly longer and broader across zygomata.

From Eutamias minimus