EOCENE. 33 



having left no persistent successors. Last of all, the Proboscidea retreated 

 to the continents of the south. 



In view of the complexity of the European record, I first present the 

 relations of the above-mentioned phenomena as displayed in the simpler 

 American system. As the present essay commences with the earliest 

 periods, I exhibit the succession in descending order on the page. The 

 horizons of the Tertiary which present distinct terrestrial faunae in North 

 America have been named the Wasatch, the Bridger, the Uinta, the White 

 River, the Loup Fork, the Equus beds, and the Champlain. The types 

 which became extinct* with the close of each of these epochs are the fol- 

 lowing : 



Wasatch. White Rivek. 



Gastornithidae. Leptictidce. 



Pantodonta. Hycenodon. 



Bridger. Ghalicotheriidee. 



BaenidcE. Hyopotamidce. 



Tillodonta. Loup River. 



Stypolophuis. Mhinoceridce. 



Dinocerata. Hippotherium. 



Uinta. Oreodontida. 



fMesodonta. Equus Beds. 



Amynodon. Megatheriidee. 



Drepanadon. 

 Tapiridce. 

 Elephas. 

 CamelidcB. 



The above table exhibits the present state of our knowledge ; it will 

 doubtless be much extended by future discovery, but not otherwise 

 modified. 



The numerous able writers on European vertebrate palaeontology have 

 more frequently recorded the appearance of types in defining their faunal 



• This means, as already mentioned, the forms which left no direct snccessoTs in the Nearctio and 

 and Palasarctic faunae. 



3 C 



