1902.] Osborn, American JEocene Primates. 1 99 



posterior basin or talonid in which the enamel is waving or 

 crenulate ; the hypoconulid has disappeared excepting on the 

 broad heel of nig ; the lower molars are thus very similar to 

 those of monkeys and it is a complete surprise to find the 

 upper molars with greatest diameter transverse and almost 

 indistinguishable in pattern from those of the contemporary 

 horses such as Orohippus. The protocone forms a low trans- 

 verse crest with the protoconules (this is a rudimentary 

 protoloph mechanically correlated with the metalophid 

 below), while the hypocone and metaconule are isolated; the 

 external cusps (paracone and metacone) are compressed 

 with apical ridges running into an external intermediate 

 mesostyle ; the anterior cingule, or parastyle, is also developed. 

 The fourth upper premolar is submolariform, with three 

 large cusps (protocone, tritocone, deuterocone) ; it also ex- 

 hibits traces of the conules (Fig. 20). The fourth lower pre- 

 molar has an elevated protoconid connected by a low crest 

 with a tritoconid and a deuteroconid. 



This genus is finely represented in the American Museum 

 by the skeleton and teeth, No. 1727 ; the upper molars are in 

 a very progressive (Telmatolestes , Hipposyus) stage. 



Family ANAPTOMORPHID^ Cope. 



Definition. — Skull brachycephalic. Post-orbital process. Facial por- 

 tion of lachrymal greater than orbital ; fossa lacrymalis in front of crista. 

 Premolars reduced, jzr-i- Grinding teeth arched, molars compressed 

 antero-posteriorly, extended transversely, tritubercular, rudimentary 

 hypocone. Short, deep, lower jaw. Lower molars with elevated 

 trigonid region, reduced paraconid, no hypoconulid. 



This family is represented by the type jaw of A. cBmulus 

 from the Bridger, the famous skull of A. homunculus from the 

 Wasatch, together with portions of four isolated jaws; also 

 possibly by a larger Upper Eocene species Microsyops uin- 

 tensis. 



Prior to Cope's description of the Bridger jaw are a num- 

 ber of specimens named by Marsh, as shown in the following 

 chronological list, which possibly are related to this family or 

 to the genus Omomys. 



