66 THE HORSE. 



that the most highly specialized members of a group 

 are not always those that survive the longest. 



The Horses. (Family Equidce.) 



As has been already stated, at about the time 

 of the world's history when the Miocene was pass- 

 ing into what we term the Pliocene epoch, there 

 were no true horses in exactly the sense in which 

 we use the word now, bub horse-like animals were 

 extremely abundant both in America and the Old 

 World, differing from existing horses in details of 

 teeth and skeleton, especially in the presence of three 

 toes upon each foot, a large middle toe and a smaller 

 one, not reaching to the ground, placed on each side 

 of it. To these animals, the step from the Anchi- 

 therium of the early Miocene, mentioned in the last 

 chapter, was not a very great one. 



Unfortunately, when remains of this type were 

 first discovered, two generic names were given to 

 them almost simultaneously — Hipparion and Hippo- 

 therium, the former being a diminutive of hippos, 

 the Greek for "horse"; the latter a compound of 

 hippos and titer ion, a wild beast, Latinized to theri- 

 um, a termination very commonly employed in mod- 

 ern scientific language when coining new appella- 

 tions for extinct animals. The first name was given 



