Fig. 116a. Type and Referred specimens of Protohippus perdiius (cast Amer. Mus. 10773); Protohippus pladdus, 

 referred specimen, Amer. Mus. 17226; Protohippus secundvs, type, American Museum 8340 (reversed in drawing). 



(Three upper figures) Superior molar series showing the relative size of the grinding teeth of the three species 

 in different degrees of size and evolution. 



(Four lower left-hand figures) Fore and hind feet of Protohippus pladdus (Amer. Mus. 17226), referred specimen, 

 associated with the superior molar teeth discovered by Troxell. 



(Lower right-hand figure) Hind foot of Protohippus secundus, type, Amer. Mus. 8340 (partly restored), associated 

 with the type superior molars. 



145 



