70 VERTEBRATES I MAMMALS. 



SUB-SECTION V. 



THE ORDER OF MUTILATA OR CETACEA, &c. 



THE Order of Mutilata comprises the mammalia which 

 are deficient in the ordinary members of locomotive or- 

 gans, and which are fitted for living in the sea. They 

 have no hind limbs, and the forward ones are paddle-like 

 and fitted for swimming. This Order as here limited 

 may include both the Sirenia and the Cetacea. Each of 

 these groups, however, is regarded by some distinguished 

 naturalists as a distinct order. 



The Sirenia Sea-Cows, Dugongs,*and Stellers are 

 whale-like in general appearance, but they have teeth 

 with flat crowns, and they have corresponding herbivorous 

 habits. They sometimes leave the water and crawl upon 

 the shore and feed upon the land vegetation. Hence 

 some naturalists class them with the Herbivora. The 

 Sea-Cows (Manatus) are ten or fifteen feet in length, and 

 inhabit the warm parts of the Atlantic. The Dugongs 

 are about the same size as the Manati, and inhabit the 

 Pacific. The Stellers are found in the North Pacific. 



The Cetacea are mammals adapted for a constant resi- 

 dence in the water. In general appearance they are 

 somewhat fish-like, excepting that their tail spreads hori- 

 zontally, instead of vertically as in fishes. They have no 

 hind feet, two small bones suspended in the flesh being 

 the only vestiges of posterior extremities. Their ante- 

 rior members are paddle-like. They are destitute of hair, 

 and covered with a smooth skin, under which is a thick 

 layer of fat called blubber. They propel themselves with 

 rapidity by the downward and upward movement of the 

 tail. In the most prominent members of the Cetacea 

 the breathing-hole, which corresponds to the nostrils of 

 other animals, is situated on the top of the head, and 

 through this the water which has be^n taken into the 



