422 



INTBODUCTION TO ZOOLOGY. 



toughness and great thickness of the skin, as manifested in 

 the Hippopotamus (Fig. 320) and other species. Hence the 

 name Pachydermata, signifying thick-skinned, is that by which 

 they have "been designated. 



The order contains but nine genera, divided into thirty-nine 

 or forty species,* and comprises the most gigantic of all living 

 quadrupeds. They are found chiefly in the countries of the 

 torrid zone. No animal whatever belonging to this order is 

 found in Australia. 



Fig. 320. HIPPOPOTAMUS. 



The Indian and the African Elephants are distinct species 

 and these terms point out the countries in which they are 

 indigenous. The Hippopotamus or "River-horse," whose 

 bulk is scarcely inferior to that of the Elephant, is peculiar to 

 Africa, and even to certain districts of that continent. There 

 are no less than seven species of Rhinoceros, which are dis- 

 tributed through both Asia and Africa. Of the group of 

 which the Swine is the representative, the Wild Boar only is 

 found in any part of Europe. The Wart Hogs belong solely 

 to Africa, and the Peccaries to America. The Tapirs, which 

 are distinguished from all other animals by their prolonged and 

 flexible snout (Fig. 291) are common to both the Old and 

 the New World. 



The Horse is universally distributed, either in a wild or 

 domesticated state. Fossil remains of a species distinct fron 



* They are thus enumerated by Berghaiis and Johnston: 

 Elephants, 2 species. Damans, 3 species. Peccaries, 2 species. 

 Hippopotamus, If Swine, 9 Tapirs, 3 



Rhinoceros, 7 Wart Hogs, 3 Horses, 9 

 t It is generally considered that there arc at least two species. 



