304 VERTEBRATE ANIMALS OF THE UNITED STATES 



-V. /. annedens Elliott. Like .Y. /. fuscipes, but with distinctive 

 cranial characters: from San Francisco Bay to Monterey Bay, and 

 inland southward. 



N. f. niacrotis (Thomas). Size small; color grayish brown; tail 

 bicolor: coastal region south of Monterey Bay. 



.Y. cinerea (Ord). Color grayish buff above, white beneath; 

 length 390 mm.; tail 160 mm.; hind foot 43 mm.; tail flattened and 

 bushy; hind foot densely furred on sole: northwestern States and British 

 Columbia; 9 subspecies. 



Subspecies of N. cinerea 



N. c. cinerea (Ord). Rocky Mountains from northern Montana 

 and the Dakotas to Arizona; central Nevada and western California. 



N. c. occidentalis (Baird). Color darker: British Columbia to 

 nbrthern California; eastward into Idaho and northern Nevada. 



xY. c. fusca (True). Color very dark: coastal region west of the 

 Cascades in Oregon. 



N . c. arizoncB (Merr.). Size very small: northern Arizona and New 

 Mexico and southern Utah and Colorado. 



.Y. c. orolestes (Merr.). Color ochraceous: Rocky Mountain region 

 from New Mexico to Montana. 



N. c. rupicola (Allen). Color paler; size smaller: southwestern 

 South Dakota; western Nebraska; eastern Colorado. 



N. intermedia Rhoads. Color grayish brown; under parts white; 

 feet white; tail black above, dull white below; length 325 mm.; tail 

 160 mm. ; hind foot 31 mm. : coastal region of California from Monterey 

 Bay southward to Cape San Lucas. 



Subfamily 4. Microtinae.-T-Meadow or field mice; voles; lem- 

 mings. Body stout, with a thick head and short ears and a short tail; 

 crowns of molars flattened and showing triangular loops of enamel: 

 distribution circumpolar; over 70 species in the United States; very 

 common animals, living in a great variety of locations, but most abun- 

 dant in well-watered grass lands, all remarkable for their great fecundity, 

 breeding usually throughout the year; their food consists mainly of 

 green vegetation, roots and bark and they are often a plague to the 

 agriculturist. This subfamily includes the Scandinavian lemmings, 

 which at irregular intervals migrate across the country in great armies, 

 eventually reaching the sea and all drowning, and also the Alpine 

 marmot, which lives in the high mountains and hibernates 8 or 10 

 months of the year. 



