312 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



as Palceomitis and Pachycena the Amblypods of the 

 genus Coryphodon, and perhaps even some Tillo- 

 donts. 



The American migrations are a little less distinct 

 in the Londinian and Lutetian epochs. It seems, 

 however, plausible to seek in them the origin of 

 several Primates, such as the Protoadaptis and 

 the Necrolemur, neighbours respectively of the 

 American Notharctidce and of the Anaptomorphidce, 

 of the Rodents of the group of the Pseudosciuridce 

 and the true Sciuridce, of the Ungulates of the 

 family of the Lophiodontidce, and perhaps also of 

 the group of the Suillian Paridigits. The sudden 

 introduction into Europe of the Chalicotheridce, 

 strange Ungulates adapted to burrowing habits, 

 seems likewise to indicate an American migration 

 at the Bartonian epoch. 



The communications between Europe and America, 

 already difficult at the end of the middle Eocene, 

 appear to cease entirely at the Ludian epoch. The 

 introduction into Europe of the Didelphidse at the 

 end of the upper Eocene, may be explained, in fact, 

 quite as well by a South American migration. 



As a set-off to this, the commencement of the 

 Oligocene marks the re-opening of the connection 

 between the two continents, clearly indicated by 

 the sudden arrival in the deposits of the upper 

 Sannoisian of the first Rhinoceros (Ronzotherium), 

 and of the Achsenodontidse (Entelodon). These 

 communications are maintained in the Stampian 

 epoch and determine the importation from America 

 into Europe of the first Tapirs, of the Amynodontidae 

 (Cadurcotherium) and of the Rodent Lagomorphs. 



