256 



MR8T LESSONS IN ZOOLoaT. 



deer, drops its horns in the autumn, though they are hol- 

 low when shed, and with a persistent core, as in the ox and 

 goat. The antelope crops grass, not, like the deer, eating 

 leaves of trees and shrubs. It is the fleetest animal on the 

 plains, though short-winded and not capable of running a 

 great distance. 



In its horns, hollow when cast off, and in the presence of 



Fia. 254. — The Prong-horn Antelope. 



a gall-bladder, which is absent in the deer family, the 

 prong-horn antelope connects the deer family with the ox 

 family [Bovidce), which is represented by the sheep, goat, 

 antelope, gazelle, and ox. 



The domestic sheep {Ovis arien) is not a natural species, 

 but an association of races whose specific origin is obscure. 

 Some authors regard the turf sheep of the Stone Age of 

 Europe as the ancestor of the domestic sheep, since forms 



