1902.] 



O shorn, American Eocene Primates. 



179 



foramen external or internal to orbit. Orbits opening into temporal 

 fossae, with or without postorbital bar. Humerus with entepicondylar 

 foramen. 



The American forms divide into three contemporaneous 



phyla as follows: 



I. HyopsodontidcB 2. N otharctidcB Os- 3. Anaptomorphidcs 

 Schlosser. bom. Cope. 



i.f,c.|,p.|,m.|=44. i.?|5f,c.i,p.|,m.|= i. ^, c. |, p. ^, m. § = 

 40; 36-32. 

 Mesaticephalic. Dolichocephalic. Brachycephalic. 

 Lachrymal canal mar- Premolars persistent. Lachrymal canal ex- 

 ginal or internal to Superior molars tri- temal to orbit. Den- 

 orbit. Dental series angular to quadrate, tal series reduced and 

 not crowded. Pre- tritubercular, pro- compressed. Premo- 

 molars slowly re- gressively sexituber- lars rapidly reduced, 

 duced. Superior mo- cular. Inferior molars Superior molars tri- 

 lars becoming sexi- with depressed, cren- tubercular, trans- 

 tubercular, quadrate. ulate talonid. versely extended. 

 Talonid elevated, Short deep jaw. A 

 with pointed cusps. postorbital process. 

 No postorbital bar. 



Family HYOPSODONTID^ Schlosser. 



Lemur avidcB ' Marsh. 



Definition. — Dentition with slight or no reduction, incisors and can- 

 ines normal; canines slightly enlarged in males; superior molars 

 progressive from tri- to sexituberculy, with progressive external 

 cingulum, but without mesostyle ; inferior molars evolved from 

 quinque- to quadrituberculy by reduction of paraconid; inferior 

 molars with hypoconulid; external cusps progressively opposite; 

 pointed cusps both on talonid and trigonid. Lachrymal foramen mar- 

 ginal or within orbit. Skull without postorbital bar. 



Analogous to the Microchoeridae and N ecrolemtir in sexittibercular 

 superior molars; differing in typical incisor and canine teeth. Anal- 

 ogous to the AdapidcB in typical incisors and canines; differing in 

 sexitubercular evolution of molars. 



Chronological List. 

 Species of Hyopsodus. 



(2) Hyopsodus paulus Leidy Bridger. 



(3) " {Microsus) cuspidatus Leidy " 



(16) ? " (Stenacodon) rarus Marsh 



' The genus Lemuravus is a synonym of Hyopsodus. 



