322 MAMMALS 



fourth stomach, where the gastric juice is mixed with it. 

 To the ruminants belong most of our valuable domesti- 

 cated animals. 



Although the camel is a ruminant, its stomach has only 

 three compartments, the psalterium not being present. 

 The dromedary has one hump and its body is covered 

 with a fine wool hair, except on the breast and knees, the 

 latter being covered with thick pads of skin. This is the 

 beast of burden used in traveling across the deserts of 

 Africa and Arabia. It is expected to go from three to five 

 days without water during these journeys, but ordinarily 

 demands water every other day. On the under side of 

 each of its feet is a large spongy pad which enables the 

 animal to travel over the sand with comparative ease. The 

 camel inhabiting central Asia has two humps. 



The llamas and alpacas, found in the western parts of 

 South America, are members of the camel family. The 

 llama is still used as a beast of burden, while the alpacas 

 arc reared for their wool which is used in the manufacture 

 cf dress fabrics. 



The third group of ungulates is represented by the ele- 

 phants. There arc only two representatives of living ele- 

 phants, the African and the Asiatic. The former is wild, 

 and valued for the ivory of its tusks. The latter is domes- 

 ticated and is usually docile and intelligent. The head of 

 the elephant is very large, and would be almost insupport- 

 able from its enormous weight were it not for the fact that 

 the bones of the head contain cells filled with air. 



The upper incisor teeth are greatly developed and form 

 the tusks; The neck is very short, but the snout is pro- 

 longed into a long flexible trunk, or proboscis. At the end 

 of the trunk are the openings of the nostrils, which are 



