JR. S. Lull — The Evolution of the Horse Family. 175 



ditions under winch it is found, may be taken as indicative of 

 a conservative forest-dwelling form in contrast with the pro- 

 gressive plains-living type. Yale Museum contains a number 

 of fine skulls and other parts of the skeleton of Mesokippus, 

 including the smaller Oreodon-bed types as well as the larger 

 species from the Protoceras beds. The former specimens 

 include a nearly perfect skull of a new-born foal of pathetic 

 interest. 



10 



IV 



Fig. 10. 

 natural size. 



, Fore foot and b, hind foot of Miohippus anceps. 

 (After Marsh.) 



One-third 



Miohippus of the John Day beds represents the seventh 

 stage in the evolution of the horse. It is larger than Miohip- 

 pus, averaging at least twenty-four inches at the withers. Dis- 

 tinctions between the two Oligocene genera are not easily 

 found, the main differences, other than size, being the shorter 

 splint of digit five in the hand, and a somewhat greater com- 



