PLIOHIPPUS. 



161 



Characters. — (Matthew, 1913, Osborn, 1918) (1) Size very large, p 2 -m 3 .180, p'-m 3 .190e; (2) protoeone prominent, 

 exceeding hypocone in size, united to protoloph by a narrow isthmus, united to hypocone when molars are over half worn; 

 (3) protoeone obliquely oval on premolars, flattened oval and relatively large on molars; (4) lingual side convex, buccal 

 side flat (m 3 ); (5) fossettes expanded; (6) indication in worn crowns of pli caballin and crochet fold in prefossette, two 



A/o. 26 6 & Tt/nt 

 A.M. " 



Plich 



Fig. 128. Type of Pliohippus nobilis Osborn, Amer. Mus. 266S. (Upper) Lateral view of maxillary, one-half 

 natural size; (lower) crown view of cheek teeth, p 2 -nr\ of the left side, natural size. 



or more enamel plications from metaloph into pre- and postfossettes (m 3 ); (6) malar fossa very deep; (7) lachrymal fossa 

 extensive, its upper border unknown. 



Matthew observes (1913) that this animal equals in dental size the Pampean Hippidium. The deeper malar fossa 

 especially distinguishes the skull. The characters of the feet are unknown. Other evidence of the presence of a very 

 large horse in the Republican River Upper Miocene is afforded by the splints of a Mts. IV which may or may not have 

 been connected with the terminal phalanges. 



