AQUATIC MAMMALS 



modified aquatically than we find it. However, its critical activities are 

 more terrestrial than aquatic, for it must seek the land for its food, of 

 which it requires a prodigious amount, and this condition is unique 

 among aquatic mammals, for no other spends the whole day in the 

 water and feeds exclusively on land. This, then, is its primary require- 

 ment — that it may walk with facility upon the land. At the present 

 time it can have no dangerous terrestrial enemies save the lion and man, 

 and there is really little reason why it should spend the most of its 

 time in the water save that it is probably more comfortable there. And 



Figure 6. Dorsal representation of Sirenia: (a) manati {Trkhechus) from 



British Guiana (redrawn from Murie, 1880) ; {b) Trichechus americanus 



(from Murie, 1872); (f) dugong (Halicore) (from a mounted specimen 

 in the National Museum). 



as it should be perfectly safe when in the water from everything except 

 a large crocodile, there seems little reason for the high specialization of 

 its nostrils and especially its eyes, which enable it to breathe and see 

 when every other vestige of its body is submerged. 

 [39] 



