118 MAMMALIA. 



elongated body ; their very movable spine, which is provided 

 with muscles that strongly flex it; their narrow pelvis; their 

 short hair, that adheres closely to the skin, all unite to render 

 them good swimmers ; and all the details of their anatomy con- 

 firm these first indicia. 



We have as yet distinguished two genera only, Phoca and 

 Trichechus. 



Phoca, Lin. 



Seals have six or four incisors above, four or two below, pointed 

 canini and grinders to the number of twenty, twenty-two, or twenty- 

 four, all trenchant or conical, and without any tuberculous part what- 

 ever ; five toes to all the feet, the anterior ones regularly decreasing in 

 length from the thumb to the little toe, while in the hinder feet the 

 thumb and the little toe are the longest, and the intermediate ones 

 the shortest. The fore feet are enveloped in the skin of the body as 

 far as the tarsus, the hinder ones almost to the heel. Between the 

 latter is a short tail. The head of a Seal bears a resemblance to that 

 of a Dog, whose intelligence and soft expressive look it also pos- 

 sesses. It is easily tamed, and soon becomes attached to its keeper, 

 or those Avhofeed it. The tongue is smooth, and sloped at the end, 

 the stomach simple, caecum short, and the intestinal canal long, and 

 tolerably regular. These animals live on fish ; always eat in the 

 water, and close their nostrils when they dive by a kind of 

 valve. As they remain a long time under water, it was supposed 

 that the foramen ovale remained open, as in the human foetus but 

 it is not so : there is, however, a large venous sinus in the liver, 

 which must assist them in diving by rendering respiration less ne- 

 cessary to the motion of the blood. Their blood is very abundant 

 and very black. 



Phoca, properly so called, or without external ears. 



The true Phocse have pointed incisors; all the toes enjoy a certain 

 degree of motion, and are terminated by pointed nails planted on the 

 edge of the membrane, which unites them. 



They are subdivided, from the number of their incisors. The 

 Calocephala, Fr. Cuv. have six above and four belowj such is the 

 Phoca vilulina, L.; Buff". XIII, xlv, and Supp. VI, xlvi ; Ph. 

 liitorea, Thienem. pi. vi. (The Common Seal.) From three 

 to five feet in length ; of a yellowish grey, more or less shaded 

 and spotted with brov/n, according to its age ; sometimes 

 brownish, with small yellow spots. When very old it becomes 

 v/hitish. Common on the coast of Europe in great herds. It 

 is also found far to the north ;*-*ve are ^vcn assured that it is this 



