332 



EVOLUTION OF THE HORSE. 



young) exceed that number. The digits, I may remark, are 

 numbered from within, outwards. Thus, the thumb on our 

 hand is termed the first digit ; the Httle finger, the fifth digit. 

 Among the ancestors of the horse, the first digit was the first 

 to disappear ; and after it, the fifth digit. In the Hyraco- 

 therium, the first digit has gone from all four feet. The fifth 

 has vanished from the hind ones, and has begun the process 



Fig. 199. — {After Gaudry) Left Front 

 Foot of Brontotherium (^th real length). 



Fig, 200. — {After Gatidry.) 

 Left Hind Foot of Bronto- 

 therium (ith real length). 



of doing so, in the front feet. The Orohippus has also lost 

 its fifth digit. The Anchitherium (like the rhinoceros) 

 appears as a true three-toed mammal ; having lost its first and 

 fifth digits. In the Hipparion gracile, the second and fourth 

 digits have begun to disappear ; and have done so, completely 

 in the horse of the present day. From the foregoing 

 considerations, its ancestors are classed among odd-toed 

 animals i^Pcrissodactyld). We must further observe that, 



