AGE OF THE AEAPAHOE AND DENVER. 235 



characterized as a Laramie fauna except by including the Fort Union in 

 the Laramie, a view formerly prevailing, it is true, but now abandoned by 

 all the recent writers on this question. As regards the reference of the 

 Converse County beds to the Laramie or post-Laramie on the occurrence 

 of these shells, their evidence would seem strongly in favor of the post- 

 Laramie. In a succeeding section the evidence concerning Black Butte 

 is reviewed and it is plain that reasonable doubts may he entertained in 

 regard to the assignment of the saurian beds at that point to the Laramie. 

 The formation overlying the Ceratops l>eds with apparent conformity on 

 the west side of the Converse County basin is said by Mr. Hatcher to 

 be of about the same thickness (3,000 feet) and constitution, but it is 

 destitute of fossils except for an abundant flora. The large number of 

 leaves sent by Mr. Hatcher to the National Museum have been examined 

 by Mr. F. H. Knowlton, who has kindly authorized the statement in this 

 place that but few identifiable species are present. The greater part of 

 the material consists of one species, Platanus raynoldsii, a representative 

 species of the Denver beds flora and also known in the Fort Union. 



Reviewing the facts given by Mr. Hatcher concerning the strata of 

 Wyoming, which have yielded the Ceratops fauna of Professor Marsh, 

 with regard to the assignment of these strata to the Laramie or Post- 

 Laramie, it appears to the writer that the question is by im means settled, 

 and that a reference to the post-Laramie has much in its favor. The inver- 

 tebrate fossils would certainly favor such a reference should any weight be 

 attached to the i>-\v species above named. And the vertebrate fauna shows 

 strong alliance with that of the Arapahoe and Denver formations, while the 

 other localities which have yielded these remains are all more or less open 

 to the suspicion that they may also be post-Laramie. The lithological 

 character of the fossil-bearing beds allies them rather with the post-Laramie 

 than with the Laramie. 



The conformity of the series with the Fox Hills is considered the most 

 weighty line of evidence by Mr. Hatcher, but in the light of the circum- 

 stances of this particular case it is clear that too much weight may easily be 

 laid upon this fact. The Arapahoe and Laramie beds seem conformable as 

 far as they have been traced along the line of the foothill fold, but the 



