34 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.63. 



4. Probably, also, as indicated by certain modifications noted in 

 the Fort Union Paromomys and Palaechthon, some of the Eocene 

 Tarsiid, at least, were rather closely related to the Notharctids, as 

 was suggested by Wortman; in which case Wortman's other sugges- 

 tion of a possible derivation of the marmoset branch of the PlatjTrhini 

 from some form of Eocene Tarsiid, as Omom.ys, is not entirely impos- 

 sible. These conjectures regarding relationships, however, can only 

 be tested by a knowledge of skull and foot structure, which, in most 

 of the early Tarsiids, is at present almost entirely wanting. 



5. Neither the Paleocene Primates nor a restudy of the Notharctid 

 group itself seems to lend any support to the views held by Gregory, 

 Stehlen, and others regarding the primitive ancestral-lemurine affini- 

 ties of the Adapidae. That they have lemurine affinities can not be 

 denied, but these Eocene Primates which were still in a primitive- 

 primate or relatively generalized stage of development, appear to 

 have been progressively advancing along lines leading definitely to- 

 ward the modern Anthropoidea, especially in the direction of the 

 Platyrrhine group; and that their relationsliip to the lemurs, though 

 apparently close to one living group, is to be traced backward from 

 the Notharctids to a more remote common ancestor and not forward 

 in geologic time. Or in other words, it may be assumed that the 

 Adapidae represent a group of Primates which, while having been 

 derived from an earher group also giving rise to the modern lemurs, 

 were as early as the Eocene already definitely progressing away from 

 the lemurine and toward the anthropoid type of development. 



6. It logically follows from the foregoing views that none of the 

 now known early Primates fulfill the conditions required of an an- 

 cestral type from which the modern lemurs (excepting only the 

 Tarsiidae and possibly the Daubentoniidae) were derived, and this 

 hypothetical group still remains to be discovered. The same may 

 possibly be said of the monkeys and apes of the Old World, at least 

 so far as the Tertiary beds of North America are concerned. But 

 the ancestral stock of these anthropoids, if found in beds of Eocene 

 age, may be expected to show very close affinities with the Noth- 

 arctinae, 



7. The combined evidence of the known Eocene and Paleocene 

 Primates indicate rather clearly that, although still relatively primi- 

 tive and generalized in anatomical structure, the evolution of the 

 Primates, even at this early time, was well under way, and we must 

 look much further backward in time than to the beginning of the 

 Tertiary for the origin of the principal major groups of this great 

 order. 



