AGE OF THE ARAPAHOE AND DENVER. 231 



a part of the so-called Laramie, but are below the uppermost beds referred 

 to that group." 



The statement that "a distinct horizon" has been "traced nearly 800 

 miles" and that -, it is marked almost everywhere" by certain fossils would 

 imply either that actual continuity bad been proved or that the stratigraphic 

 position of the fossil-bearing strata had been found to be clearly the same 

 at numerous localities not far apart. Hut win mi Professor Marsh made the 

 above assertion the Denver region was the only one in which the position 

 of the Ceratops-bearing beds had been established in complete sections, 

 and here they were found to be separated from the typical Laramie below 

 them by a great stratigraphic break; Moreover, none of the described 

 fossils was found east of the mountains between the Denver Basin and 

 Converse County, Wyo., a distance of 200 miles. As far, then, as the new- 

 fossils themselves are concerned they prove either a great extension of the 

 Arapahoe and Denver (post-Laramie of this report), or a distribution of 

 the fossils in question beyond the limits of what may properly be termed 

 one formation or horizon. 



It is plainly of primary importance to ascertain whether any of the 

 strata containing the so-called Ceratops fauna really belong to the true 

 Laramie, as distinguished from the Arapahoe, or whether they all belong to 

 the latter formation. A review of the known facts concerning the published 

 localities will now be given. 



The Ceratops beds of Converse County, Wyo. The most important localitV for tile 



Ceratops fauna as yet discovered is thai of < ionverse ( iounty, Wyo., tor the 

 reason that every species belonging to that fauna thus far described by 

 Professor Marsh from Wyoming was found there, and these species form 

 much the greater part of the total vertebrate fauna as now known. This 

 statement is made on the authority of Mr. J. B. Hatcher, now of Princeton 

 College, under whom, as Professor Marsh's assistant, all the fossils in 

 question were collected. In the original descriptions by Professor Marsh 

 the fossils were said to have been obtained in "the Laramie of Wyoming" 

 or "the Ceratops beds of Wyoming." It is important to emphasize the 

 fact that not one of the described species came from the typical Laramie 

 strata of southern Wyoming or from their demonstrated equivalent. It 



