series that has been called Laramie and in the Fort Union. Again, they 
are found in the Green River beds, in the White River beds, and in the 
deposits at Florissant, Colorado. Otherwise, the record is mostly missing. 
On the other hand, the history of the vertebrates is quite full. Between 
the Fox Hills and the present time there are known probably nearly twenty 
distinct faunas and it has been found possible to correlate these in most 
eases closely with European faunas. With such a series at command, the 
extremes of which differ enormously, while the mean terms sometimes 
grade into their successors, at other times differ greatly from the next 
comers, the paleontologist need not go far astray in determining the proper 
level of each fossil-bearing deposit. It may be remarked that when the 
paleobotanist refers the Green River beds to the Oligocene, while the ver- 
tebrate paleontologists put them at the bottom of the middle Eocene, a 
serious dislocation of views is indicated. 
- 
(. THE BEGINNING OF THE EOCENE IN EUROPE AND AMERICA. 
When one comes to correlate formations in America with those of 
distant countries great difficulties are likely to be experienced. Interrup- 
tions in stratification are not likely to occur at the same time in America 
and Europe and Asia. On account of differences in the character of the 
deposited materials, the climate, the interposition of barriers, and other 
features of environment, the contained organisms must differ to a greater 
or less extent. In the case of the beds about which exists our dispute, 
they are neither of marine origin nor in contact with strata of purely 
marine origin. Hence they cannot be compared directly with either the 
typical uppermost Cretaceous deposits of Europe, the Danian, nor with 
the Thanetian, the lowermost European Eocene. The Lance Creek beds, 
the Hell Creek beds, and others related to them have been produced 
mostly through the action of fresh waters and they contain remains of land 
plants, freshwater mollusks and fishes, reptiles inhabiting the water and 
the land, and a few terrestrial mammals. In such a situation we must 
have recourse to indirect means of correlation. 
In the vicinity of Rheims, France, in deposits belonging to the Thane- 
tian, there has been found a considerable number of genera and species 
of extinct mammals, together with some birds, reptiles, and fishes. The 
Mammals have been studied and described by Lemoine. On the strength 
of this fauna these Cernaysian beds were correlated with the Puerco at a 
[19—23008 ] 
