62 



BIOLOGICAL LECTURES. 



established beyond cavil. The following table gives this order 

 of succession of the principal fresh-water Tertiaries, omitting 

 a few that are not yet sufficiently well known for exact 

 reference. 



Pleistocene 

 Pliocene . 



Miocene . 

 Oligocene 



Sheridan stage 

 Blanco stage 

 Goodnight stage 



Loup Fork 

 John Day stage 



White River 



Eocene 



f Nebraska substage 

 (^ Deep River substage 



Protoceras beds 

 Oreodon beds 

 Titanotherium beds 



Bridger substage 



Wind River ( ? Green River) 



Uinta stage 

 Bridger stage 



Wasatch stage 

 Puerco stage 



The classification employed in this table is a little different 

 from any that has yet been published, a difference which prin- 

 cipally affects the Oligocene. Usually the John Day is called 

 Lower Miocene; the White River, Oligocene, and the Uinta, 

 Upper Eocene. The arrangement adopted in the table corre- 

 sponds to the newer classifications of the Oligocene made use 

 of in France, and has the further advantage of exhibiting the 

 close faunal connections between the Uinta, White River, and 

 John Day stages, an unbroken succession such as no other 

 three formations display. When these three successive faunas 

 shall have been recovered, reconstructed, and thoroughly 

 studied, we shall have an ideal set of phylogenetic series, 

 which will throw a brilliant light upon the processes of evolu- 

 tion. The beginning which has already been made in this work 

 encourages us in really enthusiastic expectations. Abstractly, 

 it matters little whether we call these beds Eocene or Miocene, 



