ZOOLOGY OF FOSSIL REMAINS 97 



history of this animal is a hackneyed theme but, 

 nevertheless, very convenient for reference. Al- 

 though not old in comparison with the earlier animal 

 life, a quite close series of fossil remains shows the 

 development of the horse family through a period of 

 3,000,000 years. The earliest authenticated ancestor 

 of this race began in the Eocene period with an animal 

 having a four-toed limb in front and a five-toed one 

 behind. About the size of a fox, this eohippus was 

 the ancestor of the horse tribe. From this point, the 

 descendants of the original forms show the structural 

 modifications through which the family of horses 

 passed, until we arrive at the recent horse with a 

 single toe on both fore and hind feet, with the molar 

 teeth modified and fitted for its food of grass and 

 grain. 



In the museum at Yale University and, notably, 

 in the American Museum of Natural History in New 

 York City, are preserved a large number of the fossil 

 remains of these animals. The development was not 

 that of a single kind of horse but parallel development 

 of several varieties some of which have become 

 extinct and others continued. It is a difficult 

 problem to keep separate the straight line of ancestry 

 of our modern horse, but the material now accu- 



