THE STORY OF THE HORSE 225 
the soft and tender herbage of his woodland home, 
his teeth had as yet no tendency to become special- 
ized. The molars had mounds upon them, develop- 
ing, perhaps, more into the shape of the points of the 
hog’s, but even still quite generalized teeth. His main 
enemies, from whom, perhaps, he could with little dif- 
ficulty escape, were creatures related to the hyenas 
of to-day. Perhaps, like their modern representa- 
tives, they preferred eating their flesh tainted to ex- 
erting themselves enough to capture and kill their 
prey. By the time we advance a little further into 
the Tertiary, though still in its early portion, a re- 
markable change has already come about. The fifth 
toe, which in the earliest horse hung upon the side of 
the front foot, has completely disappeared. The 
change in the hind foot has gone still further. The 
hind leg in many animals evolves more rapidly than 
the front. The heavy work of running is always 
done by the hind feet, while the front feet serve 
rather as a prop to keep the animal from falling than 
as the actual means of locomotion. Hence the hind 
feet and the muscles of the hind quarters are almost 
always heavier than the front. Possibly on the front 
foot the little fifth toe was less of an obstruction, and 
persisted after the early horse had lost the corre- 
sponding toe on his hind foot. This process has gone 
on still further in this second stage, and the hind foot 
