Mammals 33 



of the last glacial stage. The history of the bison, then, is appar- 

 ently as follows. Some time during the late Tertiary the genus 

 Bison evolved from the true oxen (Bos) in the northern part of 

 the Old World. Reaching America, the bison had time to split 

 up into several species, which roamed over what is now the United 

 States. During the glacial period, or soon after, all these became 

 extinct except the one kind now living. This, owing to the 

 depredations of the European species of Homo, which had invaded 

 the country, was nearly exterminated. But some members of 

 that pernicious (from the bison's standpoint) race regretted what 

 had been done, and took measures to keep the species alive, with 

 very good success. 



The sheep and goats are placed in a subfamily Caprinae, 

 Capra being a goat. This, however, excludes the American Moun- 

 tain Goat, which is not a true goat, but belongs to the genus 

 Oreamnos in the subfamily Rupicaprinae, being allied to the Euro- 

 pean chamois. Another genus of this group is the Asiatic Nae- 

 morhedus, which includes the serow and goral. In 1899 Cragin 

 reported that he had found traces of this genus in the Pleistocene 

 of Colorado, and called the extinct species N. palmeri, after 

 General Palmer of Glen Eyrie*. The Rocky Mountain sheep, 

 Ovis canadensis, is placed in the same genus as the domesticated 

 animal. It inhabits the higher mountains, coming down into the 

 valleys during cold and snowy weather. This splendid animal 

 is now protected, and in the spring it is often possible to approach 

 near enough to flocks in the Estes Park region to take good photo- 

 graphs. As with the Bovinae, we have here another Old World 

 group, which has invaded America very recently, geologically 

 speaking. Probably because the sheep inhabit mountain ranges, 

 and therefore tend to become isolated in colonies, they have split 

 up into numerous variously diverse species and races. The last 

 catalogue of North American mammals ( 1 924) cites no less than 

 eighteen kinds of mountain sheep, two of these inhabiting the 

 States of Chihuahua and Sonora (Mexico) respectively, while 

 another lives in Lower California. 



The American antelope is called Antilocapra americana, the 

 generic name meaning antelope-goat. It is in fact neither an 



*Mr. Warren writes that these bones are now in the U. S. National Museum, and that 

 Mr. Gidley states that they do not belong to Naemorhedus. 



