CLASS I. MAMMALIA: ORDER 6. PINNIPEDIA. 



321 



WALRUSES. 



ORDER 6. PINNIPEDIA. 



The order of the Pinnipedta, or Seals and Walruses, is distinguished from all other mammalia 

 by the peculiar structure and arrangement of the limbs. The toes of all the feet are united 

 almost to their extremities by the common integument, by which they are converted into broad 

 fin-like organs, the bones of the arm and leg being usually short, and concealed, to a great ex- 

 tent, beneath the skin of the body. The tips of the toes are armed with strong claws, and these 

 are frequently almost the only indication of their existence, although the bones are the same as 

 those of the most perfectly organized mammalia. The position of the hind-feet is very remark- 

 able ; they are placed quite at the hinder extremity of the body, and thrown backwards into a 

 nearly horizontal position on each side of the very short tail, so as to resemble the horizontal tail 

 of the whale, and, like this, they constitute the principal agents in the locomotion of the animals 

 in their natural element, the water, where they swim and dive with the greatest facility. When 

 swimming, the fore-paws are applied close to the side of the body, and are only used in turning 

 about. 



The general form of the body is particularly adapted for a residence in the water, being nearly 

 cylindrical, and tapering gradually from before backward ; the neck is short, and the head small 

 and rounded. Like the cetacea, which they resemble in their general form, the seals have the 

 surface of the body covered with a stratum of blubber, which serves the same purpose as in those 

 mammalia. The skin, however, is covered with hair of two kinds — a soft woolly down, close to 

 the skin, and a coat of long, smooth hairs, which lie close to the body, and form a shining coat, 

 offering no resistance to their passage through the water. 



i The skull and jaws are compact and powerful, and the former exhibits strong ridges for the at- 

 tachment of the muscles of the jaws. The orbits are usually continuous with the temporal fossae.. 

 The teeth are always of three sorts, but they vary considerably in number. The incisors are usu- 

 ally small, but the canines are large and powerful, curved and sharp at the point, indicating the 

 .carnivorous nature of the animals. A further evidence of this is furnished by the form of the 

 molar teeth, which are remarkable for being usually furnished with only a single root; their 



Vol. I.— 41 



