SEALS. 143 



the Order, and are known as the true Carnivores, or Cartiivora 

 Vera; of which the leading characteristic, as already mentioned, 

 is the presence of a pair of specially modified flesh-teeth in 

 each jaw, the fore-feet, and generally also the hinder pair, 

 being of the normal type, although in the Sea-Otter the latter 

 are flipper-like. On the other hand, in the Seals and Walruses, 

 which now claim our attention, there are no flesh-teeth, and 

 both pairs of limbs are modified into flippers. From the latter 

 feature, this second great sub-ordinal group of the Order is 

 known as Carnivora Piimipedia^ or Fin-footed Carnivores. 



The massive and more or less conical form of the body in 

 the Seals and their allies is too well known to demand more 

 than casual mention. The limbs, which are relatively short, 

 have their upper segments more or less completely enclosed in 

 the skin of the body ; while they are provided with five toes 

 each, connected together by webs. Unlike the land Carni- 

 vores, the first and fifth toes of each foot are stouter and 

 generally longer than the three middle ones. The tail is 

 always short. 



In regard to their teeth, it may be mentioned that, whereas only 

 in the Sea-Otter among the true Carnivores are there less than 

 three pairs of incisors in the lower jaw, in the present group 

 such a reduction is invariably the case ; while very frequently 

 also there are only two pairs of these teeth in the upper jaw. 

 In the cheek-teeth the pre-molars (generally four in number in 

 e:ch j -w) are nearly similar to the molars ; the latter being 

 generally reduced to a single pair, although in some instances 

 there are two pairs in the upper jaw. The milk-teeth are shed 

 at an exceedingly early age — sometimes even before birth, — 

 and are consequently of no functional importance whatever, 

 fwhile collar-bones are totally wanting. 



In habits, the whole of these animals are thoroughly aquatic; 

 and they are, as a rule, inhabitants of the sea, although some 



