38 THE NEXT GENERATION 



See by the diagram that while toe bones were changing in 

 this way, jaw bones and teeth were changing, too. Notice that 

 the small jaw of the smallest horse had teeth close together 

 all the way from back to front. Now trace the change. See 

 the jaws stretch out in front little by little from generation 

 to generation. 



Notice that even though the jaws grew longer, the num- 

 ber of the teeth stayed the same. Not a new one arrived to 

 fill up the gap. The front teeth stayed in front, the rest 

 stayed on the back of the jaw, a growing gap separated the 

 two sets, and that gap grew wider and wider, until our own 

 kind of horse appeared. And it is because this modern horse 

 has several inches of stretched-out jaw which carry no teeth 

 whatever, that a twentieth-century man can guide a twentieth- 

 century horse with bit and bridle. 



When you find a friendly horse some day, examine his 

 mouth and make discoveries for yourself. At the same time 

 think of his ancestors and try to imagine what men thought 

 when they first found fossil bones of that most ancient, 

 smallest horse. 



Dr. Matthew says that when its bones first came to light 

 years ago, even students of such subjects did not so much as 

 suspect that the little creature was a horse. Instead they 

 called him Hyracotherium, meaning " the coneylike beast." 

 But afterwards so many other bones were found in Nebraska, 

 Arizona, Oregon, and elsewhere, that these same students 

 were able to construct the bone pedigree of our modern 

 horse. At the same time they named the different types, 

 as the chart shows. 



They traced connections from smaller horse to larger, from 

 four toes to one toe, from foot to hoof, from short jaw to 

 long jaw, and as they did all this they saw that every bone, 



