THE ANCESTRY OP THE HORSE 141 



satisfied, one or possibly two extra toes. Sometimes the 

 toe is extra in every sense of the word, being a mere 

 duplication of the central toe; but sometimes it is an 

 actual development of one of the splint bones. No less 

 a personage than Julius Csesar possessed one of these 

 polydactyl horses, and the reporters of the Daily Roman 

 and the Tiberian Gazette doubtless wrote it up in good 

 journalistic Latin, for we find the horse described as 

 having feet that were almost human, and as being 

 looked upon with great awe. While this is the most 

 celebrated of extra-toed horses, other and more plebeian 

 individuals have been much more widely known through 

 having been exhibited throughout the country under 

 such titles as "Clique, the horse with six feet," "the 

 eight-footed Cuban horse," and so on; and possibly 

 some of these are familiar to readers of this page. 



So the collateral evidence, though scanty, bears out 

 the circumstantial proof, derived from fossil bones, 

 that the horse has developed from a many-toed an- 

 cestor; and the evidence points toward the little Eohip- 

 pus as being that ancestor. It remains only to show 

 some good reason why this development should have 

 taken place, or to indicate the forces by which it was 

 brought about. We have heard much about "the sur- 

 vival of the fittest," a phrase which simply means that 

 those animals best adapted to their surroundings will 

 survive, while those ill adapted will perish. But it 

 should be added that it means also that the animals 

 must be able to adapt themselves to changes in their 

 environment, or to change with it. Living beings can- 

 not stand still indefinitely; they must progress or perish. 

 And this seems to have been the cause for the extinction 

 of the huge quadrupeds that flourished at the time of the 

 three-toed Miocene horse. They were adapted to their 

 environment as it was; but when the western mountains 



