56 CLASS MAMMALIA. 



The Seals (Phoca, L.) 



Have four or six incisors above, four below, pointed 

 canines and cheek teeth to the number of twenty, 

 twenty-two, or twenty-four, all trenchant or conical, 

 without any tuberculous part. Five toes on all the 

 feet, those of the fore-feet decreasing gradually 

 from the thumb or great toe to the little one ; while, 

 on the contrary, in the hind feet, the great and little 

 toe are the longest, and the intermediate ones de- 

 crease in size. The fore-limbs are enveloped in the 

 skin of the body as far as the wrist, the hinder nearly 

 as far as the heel. Between them is a short tail. 

 The head of the seals resembles that of a dog, 

 and they likewise possess the kind and intelligent 

 expression of countenance peculiar to that animal. 

 They are easily tamed, and soon become attached 

 to those who feed them. Their tongue is smooth, 

 and sloping towards the end. The stomach is 

 simple, the caecum short, the canal long, and tolera- 

 bly equal. These animals live on fish; they eat 

 always in the water, and can close their nostrils 

 when they dive by means of a kind of valve. As 

 they dive for a long time, it has been supposed that 

 the botale foramen remained open in them as in the 

 foetus. But this is not the case ; there is, however, 

 a large venous sinus in the liver which assists them 

 in diving, and renders respiration less necessary to 

 the circulation of the blood. Their blood is very 

 abundant and extremely black. 



