_Comparisons._--From _E. m. silvaticus_, the subspecies from the Black Hills, _E. m. confinis_ differs in: General tone of upper parts darker, more reddish and less grayish; ventral surface of tail more tawny; skull and baculum of same size and proportions. From _E. m. operarius_, the subspecies from the Laramie Range and other mountains of south-central Wyoming, _E. m. confinis_ differs in: Rump and thighs darker; sides darker; general tone of upper parts more grayish. For comparisons with _E. m. minimus_, _E. m. consobrinus_, and _E. m. pallidus_, see the accounts of those subspecies. _Remarks._--This subspecies is endemic to the Bighorn Mountains. Intergradation between _E. m. confinis_ and _E. m. minimus_ and between _E. m. pallidus_ and _E. m. confinis_ have already been discussed in the accounts of those subspecies. _Specimens examined._--Total number, 85. _Big Horn Co._: 12 mi. E and 2 mi. S Shell, 7,900 ft., 2; 13 mi. E and 2 mi. N Shell, 8,500 ft., 2; 13 mi. E Shell, 8,300 ft., 1; 17 mi. E and 3 mi. S Shell, 9,000 ft., 8; 17-1/2 mi. E and 4-1/2 mi. S Shell, 8,500 ft, 11; 19 mi. E and 4-1/2 mi. S Shell, 9,600 ft., 1; 9 mi. E and 9 mi. N Tensleep, 8,200 ft., 4. _Sheridan Co._: Medicine Wheel Ranch, 9,000 ft., 28 mi. E Lovell, 11; 38 mi. E Lovell, Big Horn Nat. For., 9,600 ft., 10; 5-1/2 mi. W and 1-1/2 mi. S Junction U.S. Highway 14 and Wyoming [State Highway] 14, 8,480 ft., 2. _Washakie Co._: 9 mi. E and 4 mi. N Tensleep, 7,000 ft., 26; 3 mi. SE Tensleep, 4,300 ft., 1. _Johnson Co._: 5-1/2 mi. W and 1 mi. S Buffalo, 6,500 ft., 4; 7-1/2 mi. W and 1 mi. S Buffalo, 6,500 ft., 2. _Additional records_ (Howell 1929:46): _Sheridan Co._: 20 mi. from Sheridan. _Washakie Co._: Head of Canyon Creek. _Johnson Co._: Head of North Fork of Powder River. Eutamias minimus silvaticus White _Eutamias minimus silvaticus_ White, Univ. Kansas Publ. Mus. Nat. Hist. 5 (19):259-262, April 10, 1952. _Type._--Female, adult, skull and skin, No. 20050 (KU); from 3 mi. NW Sundance, 5,900 ft., Crook County, Wyoming; obtained on July 4, 1947, by H. W. Setzer; original No. 1692. _Diagnosis._--Size large; over-all tone of upper parts brownish gray; sides Ochraceous Buff; baculum as in _E. m. pallidus_.