Paleontology. 



189 



Equus: Qua- 

 ternar>- and 

 Recent. 



Pliohippus 

 Pliocene, 



Protohippus 



Miohippus : 

 Miocene. 



Mesohippus : 

 Lower Mio- 

 cene. 



Orohippus : 

 Eocene. 



Fig. 83. — Feet and teeth in fossil pedigree of the Horse. (After Marsh.) 

 a, bones of the fore-foot ; b, bones of the hind-foot ; c, radius and ulna ; 

 r/, tibia and fibula ; e, roots of a tooth ; /"and ^.crowns of upper and 

 lower molar teeth. 



