Palaeontology. 



a b c d 



189 



Equus : Qua- 

 ternary and 

 Recent. 



Pliohippus : 

 Pliocene. 



Mesohippus : 

 Lower Mio- 



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 ; 

 d, tibia and fibula ; *, roots of a tooth ; f and g, crowns of upper and 

 lower molar teeth. 



