548 LAND MAMMALS JN THE WESTERN HEMISPHERE 



event of capital importance, as showing the highly probable 

 derivation of the raccoons from ]Cynodictis and thus bringing 

 another fissipede family into rel9,tionship with the dogs. 



4. UrsidoB. 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 



^ff^^^ __.-rf=s3^ premolars are very small, single- 



- vv'^^L^i^ rooted and often shed early ; the 



(v ' ^{^^0^ carnassials have lost their trenchant 



'^%~^^^ character ; and the molars, which are 



\^ ^^^^^k usually longer than wide, are tubercu- 



^S^^ lated, somewhat resembling those of 



_ . . „, pigs. Almost all the bears Uve prin- 



FiG. 274. — Dentition of Black . ^ 



Bear {Ursus americanus) . cipally upou Vegetable food, and eveu 



i. 3. external incisor. .. ca- ^j^g p^j^j. ^ ^^^^^ fg^^g ggj^ 



nine. p. 1, first premolar. ' ^ 



p. 4, fourth premolar, and seals, wiU eat grass and berries in 

 T^^^lTt^^^ the brief Arctic summer; thus, the 

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



fourth premolar and first , , ,i 



molar, upper jaw. ous types are Unnecessary to these 



animals. The skull is not unUke 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 Umbs 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 



