The Tetrapoda: Mammals 639 



long snout, slimy tongue, and forefeet adapted for digging. They live 

 chiefly on termites. 



Order Proboscidea. — The only living members of this once wide- 

 spread order are the elephants. These latter are confined at present to 

 Africa and southeast Asia. The elephants are well known for their 

 enormous size, large trunks, and peculiar tooth development. The 

 enormous molars move forward in the jaw as they are worn by the 

 opposing tooth. When the tooth has been replaced by a successor, it 

 is shed. Usually the elephants live in large herds and feed entirely on 

 vegetable matter. The Indian elephant is famous as a work animal 

 and in this country as a circus attraction. 



Many extinct animals, including the famous mastodons and mam- 

 moths, once dwelled in this country and were members of this order. 



Order Hyracoidea. — There is but one living genus, Procavia, in 

 this order. These are the Old World conies which superficially re- 

 semble guinea pigs, but are actually related to the hoofed animals. 

 Species live in the Near East as well as in Africa. 



Order Sirenia. — Like the whales, these animals have undergone 

 extensive modification in adaptation to an aquatic life. Their forclimbs 

 are flippers, their hindlimbs have disappeared, and their tails are 

 fishlike. The tooth development, particularly that of the molars, is 

 very similar to that of the elephants. Included in this group are the 

 now extinct sea cows of the Bering Sea, the dugong of the Red Sea and 

 of the Indian Ocean, the manatee of Florida, the West Indies, Brazil, 

 and West Africa. This latter form may be the original "mermaid" of 

 sea- weary sailors. 



Order Perissodactyla. — The hoofed animals with an odd number 

 of toes are all included in this large and important order. In general, 

 these animals are large and each foot is sheathed in a cornified hoof with 

 the main axis passing through the middle toe. There are three main 

 groups. One of these includes the horses, asses, and zebras. The 

 horses and asses have been domesticated for many centuries by man 

 and are of importance as work animals and for transportation. The 

 mule is a hybrid between the horse and ass. The female parent in such a 

 cross is the horse, and the mule offspring is sterile. It is a valuable ani- 

 mal inasmuch as it has the horse's size and the ass's stamina. The second 

 group in this order includes the tapirs of Central and South America 

 and southeast Asia. These are easily recognized by their unusually 



