THE BISON. 



611 



others as a musk sheep ( Ovibos prisons Rtitimeyer). If this 

 is the case the musk sheep, or a species closely allied to it 

 formerly extended to the Middle States at or near the close 

 of the glacial period. 



We now come to the bison and ox. The American bison 



Fig. 530. Rocky Mountain Sheep or Big-Horn. From Brehm's Thierlebeu. 



(Bison Americanus Gmelin) formerly ranged from Virginia 

 and Lake Champlain to Florida, and westward from the 

 northern limit of trees to the Eocky Mountains and easterh 

 Mexico. It is now in danger of extermination, being mainly 

 restricted to a few herds on the plains. It is closely 



