62 



osborn: OLIGOCENE, MIOCENE, pliocene EQTJIM3. 



(5) Protoloph interrupted by protoconule, metaloph continuous. (6) Lachrymal preorbital fossa moderate or shallow. 

 (7) Compared with species from the Protoceras zone of South Dakota, one-ninth larger than ill. intermedins, premolars 

 somewhat more crested and hypsodont, and of slightly greater transverse width. (8) As compared with type of M. gidleyi 

 somewhat smaller in size, protocone and hypocone evenly developed. 



Fig. 40. Miohippus quartus Osborn, Amer. Mus. Cope Coll. 7267. (Upper) Skull of type, reconstructed in drawing 

 from the right and left sides. This is the skull referred by Cope to Anchitherium longicristis . One-half natural size. 

 (Lower) Superior grinding teeth of type, p^m 3 , and the incisors of the left side. Natural size. 



Fig. 41. Miohippus quartus Osborn, Amer. Mus. 7285, paratype, juvenile skull containing dp 2 ~m 2 of the left side. 

 (Upper) left side of skull, one-half natural size. (Lower) Crown view of superior grinding teeth, dp 2 -m 2 of the left side, 

 dp 4 , partly reversed in drawing. Natural size. 



Miohippus quartus, sp. now 



Plates 3.8, 4.6,8, 5.2. Text Figs. 40, 41. 



Horizon and Locality. — Middle John Day formation, Oregon, Diceratherium zone. Type collected by J. L. Wortman, 

 1879. 



Type. — Amer. Mus. Cope Coll. 7267. A skull and fragments of a skeleton. Specimens which were referred by Cope 

 to Miohippus {Anchitherium) longicristis. Paratype. Amer. Mus. 7285. 

 Type figure — Plates 3.8, 4.8, text Figs. 40, 41 of this Memoir. 



