158 



THE GEOGRAPHY OF MAMMALS 



Old World, but it is unique among all the hollow-horned 

 ruminants from the fact that it sheds its horns every year. 

 Two other genera, belonging to the family Bovidse, are 

 confined to the Nearctic Region ; these are the Rocky 

 Mountain goat (Hcvploceros), found only in the Rocky 



Fig. 32.— The Musk Ox. 

 (Ovibos moschatus.) 



Mountains (Fig. 31, p. 157); and the Musk Ox (Ovibos), 

 which ranges over the barren grounds at the extreme 

 north of the continent, and spreads into Greenland (see 

 Fig. 32). The latter, however, was also found in the northern 

 parts of the Old World until a comparatively recent epoch, 

 geologically speaking. 



I 



