40 



THE HOESE 



It will be seen from what has been already said that 

 the history of the Perissodactyles as a group offers many 

 points of interest to the naturalist. Among these are 

 its rapid extension and separation into various modifica- 

 tions, all containing numerous minor variations ; the 

 complete extinction of many of these, and the survival of 

 three branches only, all of which (except the two domes- 

 ticated species of the equine branch, which have been 

 largely multiplied and diffused by man's agency) are poor 

 in genera and species and far more restricted than 

 formerly in geographical distribution. When we con- 

 sider how extremely imperfect our knowledge of the 

 former inhabitants of the earth mast necessarily be, 

 compared with that of those now existing, it is remark- 

 able that we have already evidence enough to show that, 

 at any period we may select since the Middle Eocene 

 time, Perissodactyles were far more abundant, varied 

 and widely distributed than they are at present. This 

 is the more interesting, as it is in marked contrast with 

 what we know of the history of the other great division, 

 the Artiodactyles, the latest modification of which, 

 especially the hollow-horned ruminants or Bovidce (ante- 

 lopes, sheep, or oxen), are now the dominating members 

 of the great Ungulate order, widespread in geographical 

 range, rich in generic and specific variation, and 

 numerous in individuals. 



Of the three existing families of Perissodactyles, the 



