THE STORY OF THE HORSE 221 



gree, actually illustrated by real examples, following 

 each other in time through the geological history. A 

 few of these lines are gradually becoming plain, and 

 none of them is clearer than the pedigree of our fa- 

 miliar and much loved horse. The example is a par- 

 ticularly interesting one, not only because of our af- 

 fection for the animal, but because the horse origi- 

 nated in all likelihood in North America on the land 

 occupied to-day by our Western plains. As though 

 he loved the country of his ancestors, he returned 

 after having circled the globe, and once more went 

 wild in the home of his forefathers. The problem 

 was first worked out in Europe and later elaborated 

 in this country. Now the history gets its finest ex- 

 pression in the American Museum of Natural His- 

 tory in New York City. The collection of fossil 

 horses in that institution surpasses in completeness 

 and in excellence of mounting and of sympathetic 

 restoration any similar collection representing the an- 

 cestry of any other animal in the world. 



In the table of Geological Times, given in chapter 

 six, the era of recent life known as the Cenozoic is 

 seen to occupy something like five million years. This 

 figure, as was previously suggested, is very uncer- 

 tain, and may be three or may be six, but is safely 

 represented in millions. Through most of this time 

 stretches what is known as the Age of Mammals, the 



