CLEWS IN NATURAL HISTORY. 



27 



cause the foot of the Hipparion to sink less deep into swampy soil, and 

 be more easily withdrawn than the more simplified horse's foot." Fur- 

 thermore, the ulna or bone of the forearm, deficient in the horse of to- 

 day, is tolerably well developed in Hipparion. 



Backward in time, and in the older ' Miocene formations of Europe, 

 another fossil horse was disentombed, and was duly described under 

 the name of Anchitherium. This latter horse possesses a completely 

 developed ulna in the forearm, and fibula in the leg- ; but its chief point 

 of interest lies in the fact that each foot possessed three fully developed 

 toes (Fig. 12, DD 1 d, d, c) which apparently must have touched the 



d 



a 



6Ti 



Fig. 12. 



ground in walking. Already, our splint-bones are seen to better their 

 condition as we pass backward through the ages, and to appear as the 

 natural supports of well-developed second and fourth toes. Here the 

 geological history of the horse in the Old World may be said practi- 

 cally to end. Modern history assures us that the first horses which 

 peopled the New World, and whose descendants roam over Ameri- 

 can prairies as the famed mustangs, were imported by the Spaniards at 

 the period of the Mexican conquest. Geology has a more curious tale 

 to relate of the New World horses and their history, and gives them an 

 antiquity compared with which the events of man's primitive history in 

 either world are but as yesterday. Recent researches among the rock 

 formations of Western America, in particular, have shown us that it 

 is to the New World we must look for a perfect pedigree of the horse. 

 For, beginning with the horse of to-day, with its splint-bones, we are 

 carried gradually backward in time to the Pliocene horse of the New 

 World named Pliohippus (B B 1 ) a form not differing materially from 

 the living horse, but serving in a very graduated fashion to introduce 

 us to the older Protohippus, the New World representative of our own 

 fossil Hipparion (C C 1 ), and in some respects a more typical three-toed 



