GREGcmy: notiiarctcs, an American eocene primate 



61 



skulls and skeletons of Notharcfus and its relatives indicate, however, a somewhat nearer affinity to Adapis, 

 so that the two may be considered as divergent phyla of a single family." He accordingly refers the 

 American series to the family Adapidse. 



In 1916 Dr. Stehlin described additional species of Adapis, including the primitive Adapis priscus, 

 and in discussing the relationship of the Adapidte and the Notharctidse emphasized the fact that even 

 the oldest known species of Pehjcodus had already entered the line of specialization leading to the later 

 members of the Notharctidse and therefore can not be considered as ancestral to the Adapidse. The 

 present writer's suggestion that the differences in the molars in the Adapidse and Notharctida^ were proba- 

 bly correlated with differences in the excursion of the mandible was severely criticized. 



In his discussion of the morphological and phylogenetic significance of the tympanic annulus and 

 of the course of the internal carotid artery, which have been used by several authors as a l^asis for classi- 

 fication, Dr. Stehlin arrived at many other important conclusions which will be considered in the present 

 studies; and the same is true of his discussion of the various parts of the dentition and of his final con- 

 clusions on the classification of the primates. The memoir closed with a comparison of the successive 

 primate faunas of the Eocene of Europe and America and with a discussion of the evidence bearing on 

 the possible centers of oi'igin of the Eocene primates of Europe and of the Old World and New World 

 groups. 



In 1917 Granger and t iregory revised the numerous Bridger species of A^otharctus, describing and figur- 

 ing the types in the Peal)ody, American, and National Museums, as well as the types of the hitherto 

 undescribed stages Notharctiis inaiihewi, N'. osborni, and N. pugnax. Marsh's Telmalestes was regarded 

 as falling within the genus Notharctus. The sequence and diagnostic measurements of mi-ms of all the 

 species of Pelycodus and Notharctus were summarized in a table. A new genus, Aphanolemur, possibly a 

 member of the Notharctinse, was established. 



To recapitulate, the principal steps in the progress of om- knowledge of the Eocene Notharctidse and 

 their allies, up to the time of the publication of the present work, have been as follows: 



1. The early descriptions of fragmentary specimens of jaws and teetli hy Leidy, Marsh, and Cope. 



2. The observation by Leidy that it would require only minor structural modifications to convert 

 the jaw and teeth of Notharctus into those of a South American monkey. 



3. The recognition of the primate affinities of " Lvmnotherium" and " Tornitherium" by Marsh and 

 Cope, followed by Cope's unfortunate error in regard to the creodont-like structure of the feet of Pely- 

 codus. 



4. The detection and correction of this error by Schlosser, Matthew, and Osborn. 



5. The reduction of Limnotherium, Thinolestes, Hipposyus, and Tonrilhcriiin/ to the rank of synonyms 

 of Notharctus by Osborn and Matthew. 



6. The tracing out of the stratigraphic succession and relationships of the species, ranging from 

 the minute Pelycodus ralstoni of the Lower Eocene to the large Telmatolestcs crassus of the upper Middle 

 Eocene, by Osborn, Matthew, and later by Granger and Gregory. 



7. The recognition of the non-primate affinities of Hyopsodus and the removal of Hyopsodus to 

 the neighborhood of the Insectivora (Wortman), and finally to the Condylarthra (Matthew). This 

 disentanglement clears the way for the recognition of the true affinities of the Notharctidse. 



8. The fluctuation in opinion as to the union or separateness of the Notharctidse and the Adapidse, 

 culminating in Stehlin's demonstration that the two families followed different lines of dental evolution 

 and in the writer's conclusion that they may nevertheless be regarded as divergent subfamilies of a single 

 family. 



