2l6 



AKIMAL BIOLOGY 



the United States, however, is an intermediate form, as its 

 horns are hollow, but are shed each year. The hollow 

 horns are a modification of hair. Do solid or hollow 

 bones branch ? Which are possessed by both sexes ? 

 Which are pointed? Which are better suited for fight- 

 ing ? Why would the deer have less need to fight than 

 the cattle ? Deer are polygamous, and the males use their 



FIG. 392. ROCKY MOUNTAIN SHEEP ( Ovis montana) . x. 



horns mostly for fighting each other. The sharp hoofs of 

 deer are also dangerous weapons. The white-tail deer 

 (probably the same species as the Virginian red deer) is 

 the most widely distributed of the American deer. It 

 keeps to the lowlands, while the black-tailed deer prefers 

 a hilly country. The moose, like the deer, browses on 

 twigs and leaves. The elk, like cattle, eats grass. 



The native sheep of America is the big horn, or Rocky 

 Mountain sheep (Fig. 392). The belief is false that they 



