326 VERTEBRATE ANIMALS OF THE UNITED STATES 



and Upper Transition zones; westward to the Great Plains. Porcupines 

 climb trees for bark and twigs, which they feed on, but they are clumsy 

 climbers and live largely on the ground, nesting in holes among the 

 rocks; from i to 4 young raised annually; they do not hibernate. 



E. epixanthum Brandt. Western porcupine. Similar to E. dor- 

 satimi; tips of long hairs greenish yellow; midventral line brownish; 

 length 825 mm.; tail 165 mm.: from the upper Missouri into New 

 Mexico; westward to the Pacific; northward from California to Alaska. 



Subspecies of E. epixanthum 



E. e. couesi Mearns. Smaller and paler: Arizona. 



Family 6. Aplodontiidae. — Mountain beavers; boomers. Form 

 stout, heavy; limbs short; head broad, flat, triangular; tail very short; 

 eyes very small; feet plantigrade, 5-toed; dentition i/i, 0/0, 2/1, 2)/2>- 

 I genus. 



Aplodontia Richardson. With the characters of the family: about 

 I species; burrowing, mainly nocturnal, animals which live in colonies 

 in dense wet forests, in which they construct numerous runways and 

 tunnels, and feed on bark, leaves and twigs, laying up large stores for 

 winter use; they raise 2 or 3 young annually and do not hibernate. 



A. rufa (Rafinseque). Color umber; belly gray; whiskers white; 

 length 350 mm.; hind foot 53 mm.: Pacific Coast States. 



Subspecies of A. rufa 



A. r. rufa (Raf.). Western slope of the Cascade iMountains from 

 British Columbia into northern California. 



A. r. olympica Merriam. Color darker: Olympic Mountains. 



A. r. ranieri (Merr.). Color grayer; length 373 mm.; hind foot 

 63 mm. : on Mount Ranier. 



A. r. pacifca Merr. Color fulvous brown; belly plumbeous; length 

 325 mm.; hind foot 52 mm.: Pacific coast of Oregon. 



A. r. humboldtiana (Taylor). Color ochraceous to pinkish buff; 

 length 345 mm.; hind foot 54 mm.: coastal region of northwestern 

 California. 



A. r. calif or nica (Peters). Color grayer: the Sierra Nevada, 

 California. 



Family 7. Sciuridae. — Squirrels, marmots, etc. Arboreal or ter- 

 restrial rodents, with mostly long, bushy tails; skull with postorbital 

 processes; molars rooted and with tubercular biting surfaces: 15 or 20 

 genera and about 250 species, grouped in 2 subfamilies; cosmopolitan, 



