CARNIVORA. 



575 



able swimming apparatus, similar in its action to the horizontal 

 tail-fin of the Cetacea and Sirenia. The tips of the toes are 

 furnished with strong claws, but their powers ofterrestrialloco- 

 motion are very limited. On land, in fact, the Seals can only 

 drag themselves along laboriously, chiefly by the contractions 

 of the abdominal muscles. The ears are of small size, and 

 are mostly only indicated by small apertures, which the animal 

 has the power of closing when under water. The bones are 

 light and spongy, and beneath- the skin is a layer of fat or 

 blubber. The dentition varies, but teeth of three kinds are 

 always present, in the young animal at any rate. The canines 

 are always lon^ and pointed, and the molars are generally 

 furnished with sharp cutting edges. 



Fig. 224. — The Greenland Seal {Pfwca Groenlandica). 



The section Pinnigrada includes the two families of the 

 Seals {PJiocidcR) and Walruses (Trichecidce). The Seals are 

 distinguished by having incisor teeth in both jaws, 'and by the 

 fact that the canine teeth are not disproportionately developed. 

 They form a very numerous family, of which species are found 

 in almost every sea out of the limits of the tropics. They 

 abound, however, especially in the seas of the Arctic and 

 Antarctic regions. They live for the most part upon fish, and 

 when avviake, spend the greater part of their time in the water, 

 only coming on land to bask and sleep in the sun and to suckle 

 their young. They appear to be universally polygamous. The 

 body is covered with a short fur, interspersed with long bristly 

 hairs ; and the lips are furnished with long whiskers, which act 

 as organs of touch. The Seals are very largely captured foi 

 the sake of tneir blubber. 



