500 CLASS MAMMALIA. 



formed after very long intervals. There is generally 

 from eight to ten seconds between each inspiration, and 

 this function is sometimes suspended for half a minute 

 without apparent inconvenience. It would seem that the 

 nostrils are habitually closed, and that the act of opening 

 them is attended with some effort. The quantity of air, 

 however, that enters the lungs, must be considerable, to 

 judge from the motion of the sides, and the air expelled at 

 each expiration. The quantity of air inspired compensates 

 for the paucity of the inspirations, for few of the Mammalia 

 seem to possess so great a natural heat as the Seals. These 

 animals also have a large quantity of blood. 



The external ears are but a small rudiment of a trian- 

 gular form. They are situated below the eye, a little in 

 the rear. The bony part, however, is in the same place as 

 in other Mammalia. This rudiment is closed when the 

 animal dives. The tongue is soft, the lips extensible, and 

 in the mustachios apparently resides the greatest sensi- 

 bility of touch. They communicate with nerves remark- 

 able for size, and in which the slightest touch produces a 

 sensation. 



The teeth of the Phocse are very peculiar. Six incisors 

 in the upper jaw, and four in the lower. Canines in num- 

 ber and form like the rest of the Carnassiers. Five molars 

 on each side of the two jaws, trenchant, triangular, and 

 analogous to the false molars of the other Carnassiers, 

 except that they are a little thicker at the base, and the 

 edge is more sloped. The first of these teeth is smaller 

 than the others, and placed immediately at the base of the 

 canine. 



These observations were made upon young Seals. The 

 molars of the adult are probably more numerous, and, in 

 fact, Lepechin enumerates four more. 



The structure of this animal's limbs evidently shows, 

 that it was intended to live in the water, and all its move- 



