HISTORY OF THE PRIMATES 587 



yielded no Primates, nor anything which could be seriously 

 regarded as ancestral to them. The facts are essentially the 

 same as we have found them to be with reference to the South 

 American rodents and insectivores. All three of these orders 

 appeared suddenly and unheralded in the Deseado (Rodentia) 

 or Santa Cruz (Insectivora, Primates), and aU of them were 

 allied to African or European rather than to North American 

 types. If we may assume the existence of a land-connection 

 with Africa to account for the remarkable distribution of the 

 hystricomorph rodents, the same connection will equally well 

 explain the introduction of the Primates into South America. 



Concerning the relations of the Old and New World mon- 

 keys, Mr. Beddard remarks : "Not only are these two groups 

 of the Primates absolutely distinct at the present day, but they 

 have been, so far as we know, for a very long time, since no 

 fossil remains of Monkeys at all intermediate have been so 

 far discovered. This has led to the suggestion that the Mon- 

 keys are what is termed diphyletic, i.e., that they have origi- 

 nated from two different stocks of ancestors. It is hard, 

 however, to understand on this view the very great similarities 

 which underlie the divergences that have just been mentioned. 

 But, on the other hand, it is equally hard to understand how it is 

 that, having been separated from each other for so long a period, 

 they have not diverged further in structure than they have." * 



The fossil monkeys of the Santa Cruz beds show that, as 

 a matter of fact, the South American Primates have undergone 

 little change in the essentials of structure since that remote 

 period, and thus is removed this objection to the conclusion 

 that the Platyrrhina and Catarrhina were derived from a 

 common ancestry. In a certain sense also, the discovery of 

 \Parapithecus in Egypt has diminished the gap between these 

 two sections of the Anthropoidea. The evidence, though by 

 no means conclusive, is distinctly in favour of the derivation 

 of the South American monkeys from Old World ancestors. 



1 Beddard, op. cit., pp. 555, 556. 



