GEOLOGICAL HISTORY OF THE PRIMATES 605 



period shown on the diagram. They are later than the reunion 

 of Africa to the Mainland. But the oldest fossils of the Old- 

 World Anthropoidea occur not on the Mainland, but in Africa, 

 namely in the Egyptian Oligocene. These specimens are two 

 small mandibles to which the names Propliopithecus and Para- 

 pithecus have been applied, and a third fragment resembling 

 the latter. Propliopithecus is referred to the Simiidae. Schlosser 

 made Parapithecus the type of a new family, as he supposed its 

 dental formula to be different from that of the Cercopithecidae, 

 but I concur with Gregory's view that Schlosser misidentified 

 the teeth, and that the formula is really the same as that of 

 all other Old-World Anthropoidea. Parapithecus is therefore 

 probably a primitive member of the Cercopithecidae. The two 

 points especially worthy of notice are the surprising antiquity 

 of the true apes, and that these animals dwelt in Africa before 

 the reunion, that is, in the third period. 



At the present day there is, of course, a very sharp line, 

 not only geographically but anatomically, between the New- 

 World Anthropoidea, the Platyrrhina, and the Old-World An- 

 thropoidea, the Catarrhina. The Platyrrhina have the nostrils 

 far apart and have no bony external auditory meatus ; the 

 Catarrhina have a narrow nasal septum and possess a bony 

 external auditory meatus ; and there are minor differences. 

 As contrasted with the Lemuroidea, however, the resemblances 

 of the Platyrrhina and Catarrhina outweigh the differences 

 between them. The Platyrrhina include the two families 

 Hapalidae and Cebidae. The Catarrhina include the two families 

 Cercopithecidae and Simiidae, as well as the Hominidae. The 

 Hapalidae (Marmosets) and the Cebidae are quite distinct from 

 each other ; the relationship of the Cercopithecidae and Simiidae 

 is closer. Moreover, there are certain cross resemblances 

 between the Cebidae as such and the Catarrhina. One point 

 has perhaps special interest. The Cebidae and the Catarrhina 

 have nails on all their digits. The Hapalidae have claws on all 

 the digits, except on the hallux (first toe), which has a nail. 

 If these claws of the marmosets be primitive, as there seems 

 no reason to doubt, and if the association of the Hapalidae 

 and Cebidae be valid, we must suppose that nails were in- 

 dependently evolved by the Cebidae and the Catarrhina. 



Fossil Cebidae are found in South America as far back as 

 the Miocene, the best-known genera being Homunculus and 

 Pitheculus. The relics preserved seem to indicate that these 

 monkeys did not differ greatly from the modern representatives 

 of the family. 



We find, therefore, that the Catarrhina and Platyrrhina 

 were already established as distinct groups anatomically in 

 the Oligocene. This in itself implies a high antiquity for 



