CETACEA. 203 



with external;, though small, openings, their viviparous genera- 

 tion, the mammae with which they suckle their young, and 

 all the details of their anatomy sufliciently distinguish them 

 from fishes. 



Their brain is large, and its hemispheres well developed ; 

 the petrous portion of the cranium which contains the internal 

 ear is separated from the rest of the head, and only adheres 

 to it by means of ligaments. There are no external ears, nor 

 hairs upon the body. 



The form of their tail compels them to flex it from above 

 downwards to produce a progressive motion ; it also greatly 

 aids them in rising in the water. 



To the genera of the Cetacea hitherto admitted, we add 

 others formerly confounded with the Morses. 



FAMILY I. 



CETACEA HERBIVORA. 



The teeth of these animals have flat crowns ; this determines 

 their mode of life, and the latter induces them to leave the 

 water frequently, to seek for pasture on shore. They have 

 two mammse on the breast, and hairy mustachios ; two circum- 

 stances which, when observed from a distance as they raise 

 the anterior part of the body vertically from the water, may 

 give them some resemblance to human beings, and have pro- 

 bably occasioned those fabulous accounts of Tritons and Sirens 

 which some travellers pretend to have seen. Although in the 

 cranium the bony nostrils open towards the top, the orifices 

 in the skin are pierced at the end of the muzzle. Their 

 stomach is divided into four sacs, of which two are lateral, 

 and they have a large caecum. 



Manatus, Cuv. 



The Lamantins, or rather the Manati, have an oblong body, termi- 

 nated by an elongated oval fin; the grinders, eight in number through- 

 out, have a square crown, marked with two transverse elevationsj 

 there are no incisors nor canini in the adult; but when very young, 

 we find two very small pointed teeth in the intermaxillary bones, 



