THE 



EIGHTH ORDER 



OF THE 



MAMMALIA. 



THE CETACEA 



Are mammiferous animals without hind feet ; their 

 trunk is continued by a thick tail, which is termi- 

 nated by an horizontal cartilaginous fin, and their 

 head is united to the trunk by a neck so short and 

 thick, that scarcely any diminution from the width 

 of the body is perceptible. It is composed of cer- 

 vical vertebrae extremely slender, and partly united, 

 and, as it were, glued together. The bones of the 

 anterior extremities are so shortened, flattened, and 

 enveloped in a tendinous membrane, that they are 

 reduced to positive fins. In fact the Cetacea have 

 altogether the external form of fishes, with the ex- 

 ception that in the latter the fin of the tail is vertical. 

 Accordingly they remain continually in the water ; 

 but as they respire by lungs, they are obliged to 

 rise frequently to the surface to take in fresh supplies 

 of air. However, the characters of warm blood, 

 ears with external though small openings, vivipa- 

 rous generation, mammae for the purpose of suckling 



