166 ANIMALS OF THE PAST 



smaller, being about the size and build of a 

 pony, but they were very much like a horse in 

 structure, save that the teeth were shorter. 

 As they lived during Pliocene times, they have 

 been named " Pliohippus." 



Going back into the past a step farther, 

 though a pretty long step if we reckon by 

 years, we come upon a number of animals very 

 much like horses, save for certain cranial pe- 

 culiarities and the fact that they had three 

 toes on each foot, while the horse, as every one 

 knows, has but one toe. Now, if we glance at 

 the skeleton of a horse, we will see on either 

 side of the canon-bone, in the same situation 

 as the upper part of the little toes of the Hip- 

 potherium, as these three-toed horses are called, 

 a long slender bone, termed by veterinarians 

 the splint bone ; and it requires no anatomical 

 training to see that the bones in the two ani- 

 mals are the same. The horse lacks the lower 

 part of his side toes, that is all, just as man 

 will very probably some day lack the last bones 

 of his little toe. We find an approach to this 

 condition in some of the Hippotheres even, 

 known as Protohippus, in which the side toes 



