From _Eutamias minimus confinis_ (specimens from 17-1/2 mi. E and 4-1/2 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 borealis_ (specimens from 1 mi. NW of junction of Irons Creek and Laird River; N side Muskwa River, 4 mi. W Ft. Nelson, 1200 ft.; E side Minaker River, 1 mi. W Trutch; Beatton River, 115 mi. S Ft. Nelson; 5 mi. W and 3 mi. N Ft. St. John; S side Toad River, 10 mi. S and 21 mi. E Muncho Lake; all in British Columbia; and from Assineau River, 1920 ft., 10 mi. E and 1 mi. N Kinuso, Alberta), _E. m. silvaticus_ differs in: Under side of tail more reddish; dorsal stripes less blackish; sides slightly paler (less tawny); nasals distinctly shorter; skull distinctly shorter. _Measurements._--Average and extreme measurements of three adult males and 11 adult females of _E. m. silvaticus_ from the type locality are, respectively, as follows: Total length, 190 (189-190), 207 (202-220); length of tail, 85 (81-90), 97 (82-105); length of hind foot, 31 (30-33), 32 (31-34); length of ear, 14 (13-16), 15 (14-17); weight, 45.7 (44.6-46.5), 55.7 (50.0-68.0); greatest length of skull, 32.0 (31.5-32.6), 32.3 (31.5-33.1); zygomatic breadth, 18.5 (18.5-18.5), 18.6 (18.2-19.0); least interorbital constriction, 6.9 (6.8-7.1), 7.0 (6.4-8.1); length of nasals, 9.4 (9.2-9.6), 9.6 (9.3-10.1). _Measurements of the type._--Total length, 206; length of tail, 90; length of hind foot, 32; length of ear, 15; weight, 59.3; greatest length of skull, 32.6; zygomatic breadth, 18.6; least interorbital constriction, 6.4; length of nasals, 9.3. _Specimens examined._--Total number, 28. Specimens from South Dakota are in the United States National Museum, and those from Wyoming are in the Museum of Natural History of the University of Kansas. #South Dakota#: _Custer Co._: Custer, 3; _Lawrence Co._: Deadwood, 10. #Wyoming#: _Crook County_: 3 mi. NW Sundance, 5900 ft., 14; 15 mi. ENE Sundance, 3825 ft., 1. Acknowledgment is made of assistance, with the field work, received from the Kansas University Endowment Association. _Museum of Natural History, University of Kansas, Transmitted December 8, 1951._