_E. r. simulans_: Idaho: _Bonner Co._: Priest Lake, 1 (BS). _Kootenai Co._: 13 mi. E and 5 mi. N Coeur d'Alene, 3. _Shoshone Co._: Mullan, 1 (BS). _Clearwater Co._: 25 mi. E and 16 mi. N Pierce, 6. #Eutamias cinereicollis# (J. A. Allen) Figure 13 General tone of upper parts dark grayish tawny; size medium to large; skull large; braincase widened. Baculum: Shaft thick; keel proportionally low, 1/5 of length of tip; tip 34 per cent of length of shaft; angle formed by tip and shaft 145°; distal 1/3 of shaft slightly compressed laterally; base slightly widened; shaft long, 4.88 mm. Differs from _E. quadrimaculatus_, in keel lower, ridges on either side of tip weakly developed, angle formed by tip and shaft larger; from _E. speciosus_, _E. panamintinus_, _E. umbrinus_, _E. palmeri_, and _E. bulleri_, in shaft longer, base not markedly widened, angle formed by tip and shaft much larger. For comparisons with _E. alpinus_, _E. minimus_, _E. townsendii_, _E. sonomae_, _E. amoenus_, _E. dorsalis_, _E. merriami_, _E. quadrivittatus_, and _E. ruficaudus_, see the accounts of those species. _Specimen examined_: One from Mount Thomas, White Mountains, Apache Co., Arizona (BS). #Eutamias quadrimaculatus# (Gray) Figure 14 General tone of upper parts bright reddish; pattern inconspicuous; light and dark facial stripes strongly contrasting; size large; skull relatively small and slightly built. Baculum: Shaft thick; keel relatively low, 1/4 of length of tip; tip 27 per cent of length of shaft; angle formed by tip and shaft 120°; distal 1/3 of shaft slightly compressed laterally; base slightly wider than shaft; shaft long, 4.35 to 5.28 mm. Differs from _E. speciosus_, _E. panamintinus_, _E. townsendii_, _E. umbrinus_, _E. palmeri_, and _E. bulleri_, in shaft markedly longer; base not markedly widened; angle formed by tip and shaft larger; tip proportionally shorter. For comparisons with all other species of chipmunks from western North America, see the accounts of those species. _Specimens examined_: 4. California: _Plumas Co._: Mountains near Quincy, 1 (BS). _Placer Co._: Blue Canyon, 1 (NM). _Alpine Co._: Markleeville, 1 (BS); N fork Stanislaus River, 1 (BS). #Eutamias speciosus# (Merriam) Figure 15 General tone of upper parts bright; light and dark elements of color pattern strongly contrasting; outer stripes broad and strikingly conspicuous; size medium; skull moderately broadened; dorsal outline of skull strongly arched in profile; upper incisors short and sharply recurved. Baculum: Shaft thick; keel of medium height, 1/3 of length of tip; base of keel 1/3 of length of tip; tip 47 to 55 per cent of length of shaft; angle formed by tip and shaft 90°; distal 2/3 of shaft markedly compressed laterally; base markedly wider than shaft; shaft short to medium, 2.11 to 3.17 mm.