118 Balh'ii — The Amrrirnn J^olrs of tJte Genus Evofornys. 



Tail about oO mm. knv^, thick, and densely 



bristly ridilus. 



Tail aljout 33 mm. long, not very thick or 



densely bristly dairsoui. 



Size small, hind foot lS-19 mm., dorsal stripe not 

 ferruginous. 

 Smallest of the genus, foot IS, dorsal stripe 



dark, rich chestnut in summer lorhujl. 



Slightly larger, foot 19, tail relatively shorter, 



dorsal stripe pale chestnut in summer . . brevicaudus. 

 Dorsal stripe not sharply defined, blending with color 

 of sides. 



Tail indistinctly bicolor, dorsal stripe dull 



brownish wranglei. 



Tail distinctly bicolor, dorsal stripe plain 



chestnut rhoadsi. 



Ears gray or duiihj, not distinctly rufous-tipped. 



Posterior edge of palate straight, colors bright, tail bicolor. 

 Dorsal stripe not sharply defined (dark chestnut in 



summer pelage) carol iiiensis. 



Dorsal stripe sharply defined (hazel or chestnut). 

 Sides clear, l)right gray, skull long and narrow, 



hind foot 20 idaJioensis. 



Sides dark huffy gray, skull wide and angular, 



hind foot 18.... nirarius. 



Posterior edge of palate with a median projection, colors 

 dark in all but mazavia. 

 Colors dusky or blackish above. 



Tail unicolor or nearly so, dusky or blackish, hind 



foot 18 occidentalis. 



Tail bicolor, ])lackish above, whitish below, hind 

 foot aljout 21. 

 Tail long, colors dark, skull thick and wide 



interorbitall}' cdlifornicns. 



Tail shorter, colors not so blackish, skull 



slender and narrower interorbitally ob.^ciirus. 



Colors not dusky or blackish. 



Dorsal area dull hazel, sides grayish, skull broad, 

 angular, and flat- topped mazama. 



Evotomys rutilus (Pallas). 



Mus ridilus Pallas, Nov. Sp. Quad. Glirium, 246, pi. xiv B, 1778. 



Geographic distribution. — Arctic regions of America, Europe, and Siberia. 



Type locality. — Siberia, east of the Obi. 



Genend characters. — Rather largo and Ijright colored; always recogniz- 

 able by the short, thick, bristly tail and stout hind feet ; fur long and 

 soft ; feet and ears densely haired. 



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