548 LAND MAMMALS IN THE WESTERN HEMISPHERE 



event of capital importance, as showing the highly probable 

 derivation of the raccoons from 'fCynodictis and thus bringing 

 another fissipede family into relationship with the dogs. 



4. Ursidce. Bears 



The present distribution of the bear family is all but ex- 

 clusively northern, as there is but one African species, confined 

 to the northwestern corner of that continent, and one in the 

 Andes of Peru and Ecuador, all the others belonging to Eurasia 

 and North America. 



Structurally, the family is very distinct and the dentition 

 is quite peculiar. The incisors and canines resemble those of 



other Fissipedia ; the three anterior 

 premolars are very small, single- 

 rooted and often shed early ; the 

 carnassials have lost their trenchant 

 character ; and the molars, which are 

 usually longer than wide, are tubercu- 

 ^S^ lated, somewhat resembling those of 

 pigs. Almost all the bears live prin- 



FiG. 274. — Dentition of Black .^ ^ 



Bear (Ursus americanus) . cipally upon Vegetable food, and even 



i. 3, external incisor. c. ca- ^j^^ p^j^^. g^^^ ^Yiich feeds UpOU fish 



nine. p. 1, first premolar. ' ^ 



p. 4. fourth premolar, and scals, will eat grass and berries in 



m. 1, first molar. — Below is ,i i • r » ,• ,i .i 



a view, on a larger scale, of ^^6 brief ArctlC SUmmer ; thuS, the 



the grinding surface of the shearing teeth of the strictly carnivor- 



fourth premolar and first . , , i 



molar, upper jaw. o^^ types are uunecessary to these 



animals. The skull is not unlike that 

 of the dogs in shape, but the tympanic bullae are much flattened 

 and the entrances to them are long, bony tubes, while the cranial 

 foramina are nearly as in the dogs. The body is very heavy 

 and the tail always short. The limbs are short and thick ; 

 the humerus has lost the epicondylar foramen in all existing 

 species except the South American Spectacled Bear {Tre- 

 marctos ornatus). The plantigrade feet . have naked soles 

 (except in the Polar Bear) and each foot has five well-developed 



