266 Descriptive Zoology. 



fishes, etc., and the water passes through these strainers 

 and out at the sides of the mouth. Underneath the skin is 

 a thick layer of fat which furnishes the whale oil. Such a 

 layer of fat protects this warm-blooded animal in the icy 

 water of the arctic seas. Since the discovery of our oil 

 fields the whale fishery has declined. The "spouting" of 

 whales is not due to a column of water, but to mucus and 

 the condensed moisture of the breath. 



Whales over fifty feet long are not often taken, though 

 the sperm whale is sometimes seventy-five feet, and the 

 " sulphur-bottom," found in the Pacific, is said to reach even 

 a hundred feet. It is the largest living animal. Porpoises 

 are smaller members of the same group. 



The Sea Cows. Some authors class these with the 

 whales, but they are herbivorous animals, having grinding 

 molars and a hairy covering. They seem to stand between 

 the whales and the ungulates. They live in the mouths of 

 large rivers ; the manatee is found in Florida and on the 

 west coast of Africa, the dugong in India and Australia. 

 They are sometimes killed for their flesh, which is said to 

 be very much like beef. 



The Hoofed Mammals. The horse and cow may stand 

 as examples of this order, the ungulates. The hoofs are 

 excessive developments of what correspond to our nails or 

 the claws of other animals. In many forms the hoof en- 

 cases the whole of the lower surface of the foot. It appears 

 to be a special adaptation for the support of heavy animals, 

 many of which have to run rapidly over rough or even 

 rocky ground. The number of toes is typically five, though 

 no living ungulate has more than four. They are all 

 digitigrade, that is, they walk on the toes. They are all 

 herbivorous, with teeth adapted for grinding. This is a 

 large order, and its members are of a large average size. 



