124 rROCEEDIXGS OF THE ACADEMY OF [Jan., 



the primitive throe-cusped molar, which was in all certainty that 

 typical of the earliest lemuroids. 



The better agreement of this hypothesis with the successional 

 relations shown by paltTDontology, must be emphasized, for as far aa 

 can now be determined, apes of anthropoid character, such as 

 Pliopithecus and Dryopithecus, were already differentiated in the 

 middle Miocene, at which time, or even later, monkeys appear to 

 have been represented only by such intermediate forms as Meso- 

 pitheciis. No existing genus of catarrhine monkeys is known from 

 earlier deposits than Pajno and Macacus from the Sivalik beds of 

 lower Pliocene age, in which deposits other remains have been 

 found which there is reason to regard as referable to Anthro- 

 popithecus and Simla. The fact that before monkeys as now known, 

 began to exist, man -like apes were far advanced in development, 

 and that the earliest evidence of existing genera of apes is coeval 

 with that of existing genera of catarrhines, tells enormously in 

 favor of the early and independent origin of anthropomorpha. 



The objections to this view which arise from the closer corre- 

 spondence of anthropomorpha with moukevs, rather than with 

 lemurs, in many soft parts of the organism, are not to be over- 

 looked ; but the remarkable differences in placentation and in the 

 anatomy of the sexual organs disclosed by closely related genera, 

 and even species, in other groups; the smooth brains of marmosets 

 among monkeys, and the readily adaptable character of muscular 

 dispositions, and all structures relating to locomotion, renders these 

 characters of more or less uncertain value in classification. 



It is no part of the pi-esent purpose to inquire closely into the 

 corresponding stages in the pedigree of the remaining Primates, to 

 do which, indeed, we are yet too ignorant of many essential 

 details, but this much may be said : the Nyeticebidce, which sug- 

 gest so many human and simian traits, are far from being typical 

 lemurs, with which in general structure the monkeys show much 

 agreement; but catarrhines and platyrrhines are wide enough apart 

 in many ways, and the period during which they have been thus 

 separated is so immeasurable, as to suggest Ihe greater probability 

 that their chief characteristics were already differentiated in their 

 respective Tertiary forerunners. The remarkable fact that some 

 platyrrhine genera, as Ateles, present traces of nearly all the modi- 

 fications which have been noted as characteristic of anthropomorpha 



