CARNARIA. CARNIVORA. 107 



of the earth, or elevated a little above it. It is 

 necessary that they be thus constantly bathed in 

 air ; for an interruption of the process of respiration, 

 for only a few seconds, would cause instant death. 

 But the tribe before us, the last of the Carnaria, 

 is in its habits and motions essentially aquatic, and 

 though its respiration is still exclusively aerial, yet 

 it is suspended for long intervals, usually a quarter 

 of an hour ; and sometimes, as in a case witnessed 

 by F. Cuvier, extending to an hour. Notwithstand- 

 ing this peculiarity the blood is abundant and very 

 hot; it is, however, also very black. Intended to 

 pursue the fishes that glide so swiftly through the 

 depths of ocean, the Amphibia are perfectly formed 

 for this object; and while we find in them all the 

 organs common to terrestrial animals, it is highly 

 interesting to behold how beautifully and skilfully 

 each is modified in form to correspond to the re- 

 quired change of habit. None can look upon a Seal, 

 without being at once struck with its fish-like shape ; 

 the rounded chest tapering away to a point, which 

 is the most favourable form for rapid progression 

 in water. To counteract the chilling influence of 

 the medium in which they dwell, the whole body is 

 encased in a thick layer of highly elastic fat, which 

 also resists the pressure of the superincumbent water 

 at great depths, and renders the whole animal specifi- 

 cally lighter, three very important purposes. The 

 skin is clothed with thick, downy, wool ; but as 

 this would impede swift motion, it is covered with 

 an outer coat of close, strong, shining hair. The 



