_Specimen examined_: One from Big Cottonwood Meadows, S of Mount Whitney, 10,000 ft., Inyo Co., California (CN).
Coloration varying from light to dark depending on subspecies; size small to medium; rostrum short and stout.
Baculum: Shaft thin; keel low, 1/5 of length of tip; tip 18 to 28 per cent of length of shaft; angle formed by tip and shaft 125°; distal 1/2 of shaft slightly compressed laterally; shaft short to long, 2.44 to 4.35 mm.
Differs from _E. speciosus_, _E. panamintinus_, _E. umbrinus_, _E. palmeri_, and _E. bulleri_, in shaft thinner, base not markedly widened; from _E. quadrivittatus_, _E. ruficaudus_, _E. cinereicollis_, and _E. quadrimaculatus_, in shaft thinner, tip shorter; from _E. amoenus_, in tip less than 28 per cent of length of shaft; from _E. dorsalis_, in angle formed by tip and shaft smaller; from _E. townsendii_, in tip less than 28 per cent of length of shaft, angle formed by tip and shaft 125° instead of 130°; from _E. sonomae_, in ridges on either side of tip less well-developed, keel higher; from _E. merriami_, in shaft shorter (less than 4.40 mm.), base not incised, tip proportionally longer.
For comparison with _E. alpinus_ see the account of that species.
In most places where _E. minimus_ and _E. amoenus_ occur together they can be distinguished without recourse to the baculum, but at Banff and Canmore in western Alberta, recourse to the baculum is almost necessary. There, as elsewhere, they can be distinguished readily by the shape of the bacula.
_Eutamias minimus borealis_: Alberta: Canmore, 1 (BS).
_E. m. cacodemus_: South Dakota: _Shannon Co._: Quinn's Draw, Cheyenne River, 1 (NM); 14 mi. N and 5 mi. W Rockyford, 3,200 ft., 1.
_E. m. confinis_: Wyoming: _Big Horn Co._: 17 mi. E and 3 mi. S Shell, 9,000 ft., 1; 9 mi. E and 9 mi. N Tensleep, 8,200 ft., 1. _Washakie Co._: 9 mi. E and 4 mi. N Tensleep, 7,000 ft., 1.
_E. m. consobrinus_: Montana: _Madison Co._: 26 mi. NW West Yellowstone, 6,100 ft., 1. Wyoming: _Sublette Co._: 5 mi. E and 9 mi. N Pinedale, 9,100 ft., 2. _Uinta Co._: 10 mi. S and 1 mi. W Robertson, 8,700 ft., 1; 13 mi. S and 2 mi. E Robertson, 9,200 ft., 2. Utah: _Uintah Co._: Paradise Park, 21 mi. W and 15 mi. N Vernal, 10,050 ft., 8. Colorado: _Jackson Co._: 9-1/2 mi. W and 2 mi. N Walden, 8,400 ft., 1.