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THE AMERICAN NATURALIST [Vol. XLV 



ancestors of the living forms, and as yet no record has 

 been found of the forms intermediate between those on 

 America and the living types. In the case of the Mada- 

 gascar form, Chiromys or the aye-aye, we have a repre- 

 sentative of the group which has adopted a gnawing habit 

 to get grubs, etc., under the bark, and a great change 

 has resulted in the dentition, by which the first incisor 

 has become specialized into a rodent-like gnawing tooth 

 and there is a reduction in the teeth so that the formula 

 is only 1 /, Vo, Vo, % = 18. 



The easterly wave of migration is represented by sev- 

 eral species of Adapis found in the middle and upper 

 Eocene of England and France. Apparently the prog- 

 ress of this easterly migration was slower, so that they 

 reach Europe considerably later than the same latitude 

 in America. The primates are not in the front wave of 

 immigration on the European side, so that it is possible 

 that the forested condition was not as favorable. The 

 Adapiidae in Europe, small primates with a long low 

 skull and the ancestral dental formula %, Vi, % % = 40, 

 the teeth being very generalized. 



With the close of the Eocene the first adaptive radia- 

 tion of the Primates was complete, and they had achieved 

 an almost world-wide distribution. At the end of the 

 period the North American contingent was extinct, the 

 South American group was isolated, the Asiatic and 

 African forms were scattered on islands and on the Afri- 

 can continent, and the European contingent was located 

 in central and southern Europe, or what land there was 

 at that time in those regions (see Fig. 3) ; and it is among 

 these that the next act in the great primate drama took 

 place. 



The Oligocene period is one in which there was a grad- 

 ual rising or emergence of continental areas so that the 

 southern part of Europe was an archipelago, which to- 

 ward the end developed into a long peninsula, extending 

 from the present Asia Minor (see Fig. 3). During this 

 period the change in the Adapiida? is but little known, but 



