230 GEOLOGY OF THE DENVER BASIN. 



obtained were given only in general terms. It was said that it was found 

 "in place, in the Laramie deposits of the Cretaceous, in Montana * * *." 

 ••TIk associated fossils found with the present specimen are remains of 

 other dinosaurs, crocodiles, turtles, and fishes, mostly of Cretaceous types. 

 Tin' mollusks in the same beds indicate fresh-water deposits." It is also 

 remarked that "remains of the same reptile, or one nearly allied, had 

 previously been found in Colorado, in deposits of about the same age, by 

 Mr. G. II. Eldridge." In fact all the remains found by Mr. Eldridge came 

 from the Arapahoe strata, so that the horizon of this species in the Denver 

 Basin is indicated. 



In April, 1889, Professor Marsh described Ceratops horridus, 1 the local- 

 ity and horizon being stated as follows: 



"The present specimen is from the Laramie formation of Wyoming, 

 but fragmentary remains, which may be referred provisionally to the same 

 species, have been found in Colorado." 



The latter reference is to material from the Denver beds. The species 

 was Inter assigned to the new genus Triceratops. 



The genus Triceratops was established by Professor Marsh in August, 

 1889, 2 with three species. The type "was discovered in the Laramie 

 formation of Wyoming." "A much smaller species is represented by 

 various remains probably from the same horizon in Colorado." The type 

 of this smaller form, T. galeus, was in fact obtained by Mr. Eldridge in the 

 Arapahoe beds of the Denver Basin. 



In December, 188!', one year after the description of the first recog- 

 nized Ceratops, Professor Marsh gave a description of the skull of the 

 Ceratopsidse, prefacing it with some remarks on the geological occurrence. 3 

 lie asserted that "the geological horizon of these strange reptiles is a 

 distinct one in the Upper Cretaceous, and has now been traced nearly sod 

 miles along the eastern flank of the Rocky Mountains. It is marked almost 

 everywhere by remains of these reptiles, and hence the strata may lie called 

 the Ceratops beds. They an- fresh-water or brackish deposits, which form 



1 Am. Jour. Sei.,3il series, Vol. XXXVII, p. 334. 

 -Am. .lour. Soi., 3d series, Vol. XXXVIII. p. 173. 

 Am. .lorn. Sci., M series, Vol. XXXVIII, p. 501. 



