478 



GEOLOGY OF THE DENVER BASIN. 



fig. 24. The great importance of the discoveries made here, both from a 

 biological point of view and as accurately defining the geological horizon 

 of the Ceratops beds, made it desirable to fix definitely the position of 

 every important specimen found, and these were carefully noted at the 

 time each discovery was made. As the skulls of the gigantic Ceratopsida? 

 are most characteristic, the precise localities of 30 of these skulls are given 

 in this map, so that the horizon and its age may thus be verified by future 

 explorers. 



Fig. 24.— Map of Converse County, Wyo., showing localities where skulls of Ceratopsidse have been discovered. 



The position of each skull is indicated by a cross, and inure than 30 of these specimens were found within the ana 

 bounded by the Cheyenne River and the dotted line. The localities given are based upon field notes made, at the request 

 of the writer, by his assistant, Mr. J. B. Hatcher. 



Slid farther north, in the Judith Basin, in Montana, the same lacus- 

 trine strata alternate with beds in which brackish-water invertebrates and 

 marine reptiles arc found associated with the gigantic Ceratopsidse. Along 

 this Ceratops horizon for hundreds of miles the experienced collector can 

 find vertebrate fossils at almost every exposure. 



