THE STORY OF THE HORSE 23 1 



gap in the row of the horse's teeth which makes it 

 possible for us to insert the bit into his mouth. 



Now comes a strange accident into the Hfe of our 

 American horse. Creatures of the same kin had been 

 evolving in Europe and Africa, but the developments 

 are more distinctly horselike, it would seem, in our 

 own country. Then for some reason the horse disap- 

 peared completely from American soil. Doubtless 

 two things happened. First of all, some of them mi- 

 grated across a stretch of open country which then 

 connected America with Asia in the neighborhood of 

 Bering Strait. These creatures spread first over Asia 

 and then over Africa and Europe, leaving their skele- 

 tons scattered over this enormous stretch of country. 

 Asses and zebras are still found abundantly and widely 

 scattered, but the wild horse of to-day is seen only in 

 western Asia. What happened to those who remained 

 in America we shall possibly never know. Some sur- 

 mise that a fly not unlike the tsetse-fly of Africa 

 killed them out. Perhaps the members of the cat fam- 

 ily, which are steadily growing larger and fiercer, fed 

 on their young if not upon the older ones, and ex- 

 terminated them. Perhaps the Glacial period which 

 followed was too cold for them. But, whatever may 

 have been the cause these horses died out not only in 

 North but also in South America, to which country 

 they had spread. 



