MAMMALIA 



101 



numerous simple teeth, is a familiar British species, while the 

 Greenland or Right Whale (Bakzna mysticetus] is an example 

 of the large toothless forms, which feed on shoals of minute 

 marine organisms, from which the water is strained by numerous 

 plates of whalebone (baleen) projecting downwards from the 

 palate (fig. 68). 



Order 7. SEA-Cows (Sirenia) 



This small order includes only two living genera of aquatic 

 mammals, inhabiting the shores of the Atlantic and Indian Oceans, 



Fig. 69. The Manatee (Manatus) 



and also making their way up some of the large rivers. As might 

 be expected, considering their mode of life, they are shaped not 

 unlike Cetaceans, with which they agree in the general shape of 

 the body, absence of hind-limbs, and possession of a horizontally- 

 flattened tail fin and flipper-like fore-limbs. They are not, how- 

 ever, quite so much specialized, for there is a fairly-well-marked 



