CLASS MAMMALS: ORDER UNGULATA. 



73 



The Musk Deer of Thibet has no horns, the male having 

 two sharp projecting 

 upper canines. It fur- 

 nishes the musk of 

 commerce, which it 

 secretes in a kind of 

 pouch. 



Hippopotamidae. 

 The Hippopotamus of 

 Africa is amphibious, 

 with horizontally-pro- ^ 

 jecting lower incisors 

 and strong vertical 

 canines. A greedy feeder, it sinks to the bed of the sluggish 

 stream, where it can remain six or eight minutes, digs up a 

 quantity of aquatic vegetation, rises to the top, and, washing 



Fig. no. 



Moschua moschiflrae. Musk deer. 



M'ppopMmua amphitms. Hippopotamus. jV 



the mass, devours it while leisurely floating on the surface. It 

 is exactly fitted to dredge the rivers and keep open the chan- 

 nels, so apt to become filled with the luxuriant growth of 

 that tropical region. 



Suidse. — The Hog's skull is adapted to rooting in the 

 ground for food, the lower canines projecting nearly horizon- 

 4 



