EVIDENCES OF EVOLUTION 31 



more to the open. Even in regard to the 

 teeth we can understand that the change 

 from the short-crowned to the long-crowned 

 type enabled the animals, as Dr. Matthew 

 notices, " to subsist on the hard, comparatively 

 innutritious grasses of the dry plains, which 

 require much more thorough mastication 

 before they can be of any use as food than do 

 the softer green foods of the swamps and 

 forests." 



We must not leave this question of the 

 horse's evolution without calling attention to 

 a fact of great interest, that in the individual 

 development there is a series of changes which 

 to some extent correspond with the historical 

 steps represented by forms like Eohippus, 

 Mesohippus, Protohippus, Merychippus, and so 

 on. Professor Cossar Ewart has shown, for 

 instance, that the small nodule at the end of the 

 splint bone is separate in the embryo, and is 

 the representative of one or more of the joints 

 of the second or the fourth digit which, apart 

 from this, would seem to have entirely passed 

 away. It is well known that in a monstrosity 

 of our familiar one-toed horse the splint bone 

 on each side of the main cannon-bone is en- 

 larged, and bears a complete digit, so that a 

 three-toed horse, such as the one Julius Caesar 

 rode, occasionally still walks upon the earth. 





