VERTEBRATA: MAMMALIA. 739 



number of praemolars and a single molar on each side ; but the true molars 

 are caducous, so that the dental formula of the adult animal is 



= i*. 



oo i i 33 oo 



Except as regards its dentition, the Walrus agrees in all essential re- 

 spects with the Seals. It is a large and heavy animal, attaining a length 

 of from ten to fifteen feet or upwards. The body is covered with short 

 brownish or yellowish hair, and the face bears many long stiff bristles. 

 There are no external ears. The chief use of the tusk-like canines appears 

 to be that of assisting the unwieldy animal to get out of the water upon 

 the ice; but they doubtless serve as weapons of offence and defence as 

 well, and they are used for digging up burrowing shell-fish out of the sand. 

 The Walrus is hunted by whalers, both for its blubber, which yields an 

 excellent oil, and for the ivory of the tusks. It is found, living in herds, 

 in the Arctic seas, being especially abundant at Spitzbergen and Nova 

 Zembla. 



SECTION II. PLANTIGRADA (ARCTOIDEA). The Carnivorous 

 animals belonging to this section apply the whole or the 

 greater part of the sole of the foot to the ground (fig. 424, A) ; 

 and the portion of -the sole so employed is destitute of hairs 

 in most instances (the sole is hairy in the Polar Bear). From 

 the structure of the foot, the Plantigrada have great power of 

 rearing themselves up on the hind-feet. They approach the 

 Insectivora in their comparatively slow movements and their 

 nocturnal habits, and in possessing no caecum. They mostly 

 hibernate, and their feet are always pentadactylous. 



The typical family of the Plantigrade Carnivora is that of 

 the Ursidtf. or Bears, in which the entire sole of the foot is 

 applied to the ground in walking. The Ursidce, are much less 

 purely carnivorous than the majority of the order, and, in ac- 

 cordance with their omnivorous habits, the teeth do not ex- 

 hibit the typical carnivorous characters. The incisors and 

 canines have the ordinary carnivorous form, but the " carnas- 

 sial " teeth have tuberculate crowns, instead of a sharp cutting- 

 edge. The dental formula in Ursus (fig. 428) is 



,'3-3. c *=} pm 4=4 . m 2-2 = 

 33 i i 44 3-3 



The dental formula of the Bears is thus the same as that of the 

 Dogs ; but the second and third praemolars are small and 

 usually deciduous; while the first prsemolar is also often 

 caducous. The last praemolar and all the molars have tuber- 

 culate crowns, and the carnassials are not of specially large 

 size, these characters being equally present in the flesh-eating 

 Polar Bear and the strictly vegetarian Sun-bear. 



The claws are formed for digging, large, strong, and curved, 

 but are not retractile. The tongue is smooth ; the ears small, 



