J. B. Hatcher — Ceratops Beds of Wyoming. 141 



had previously been described from the typical Laramie, ;is 

 first defined by Mr. Clarence King, and the consequent lack of 

 vertebrate forms known to have come from the Laramie for 

 comparison with those found in the Ceratops beds, it must be 

 admitted that the vertebrate fauna of the latter is, in itself, at 

 present not sufficient proof to establish the Laramie age of 

 the Ceratops beds. 



Fortunately the Ceratops beds contain an extensive inverte- 

 brate fauna, in which Dr. C. E. Beecher has identified the 

 following : Onto Couesii, White, Sphmrium formosurn, M. 

 & H., Linncea compactilis, Meek, Oampeloma multilineata, 

 M. & H., Tulotoma Thompsonii, White, and others known 

 from the typical Laramie, some of which are characteristic of 

 it. The invertebrate fossils may, therefore, be considered as 

 additional evidence of the Laramie age of the beds. 



But the most conclusive evidence that the Ceratops beds 

 belong to the Laramie period is that afforded by their actual 

 position in regard to the Fox Hills. As stated above, they 

 conformably overlie the Fox Hills, which is the normal posi- 

 tion of the Laramie. This conformability must be regarded 

 as an actual and not an apparent one, since it is shown in an 

 almost continuous. exposure for many miles along the south- 

 eastern border of the beds, where they are upturned at an 

 angle of from 16° to 29°, and where an unconformability, if 

 any existed, would be plainly visible. 



The evidences in favor of referring the Ceratops beds to 

 the Laramie are : 



(1) They conformably overlie the Fox Hills sandstones and 

 contain both a reptilian and a mammalian fauna, with decided 

 Mesozoic affinities. Among the reptiles, the Dinosaurs are, in 

 degree of development and point of numbers both as to indi- 

 viduals, and genera and species represented, probably unsur- 

 passed in any previous smilar division of the Mesozoic ; while 

 as regards degree of specialization, they are superior to all 

 previous forms. This age was preeminently an age of reptiles. 



(2) They contain an invertebrate fauna comprising many 

 forms identical with those already described from the typical 

 Laramie, some of which are unknown except in the Laramie. 



(3) They immediately and conformably overlie the Fox 

 Hills, and show evidence of a continuous deposition through 

 both series. 



Probable Conditions attending the Deposition of the Ceratops 



Beds. 



The change from marine to fresh-waters which took place at 

 the close of the Fox Hills and the beginning of the Laramie 

 was brought about by the great continental elevation going on 



