AGE OF Till' ABAPAHOE AND DENVER. 237 



Ceratopsida: from Black Butte, Wyoming. "While nolle of the tVpes < li -SI 'H I M •( 1 I > V 



Professor Marsh come from the typical Laramie of southern Wyoming, a 

 representative of this family was described from Black Butte by Professor 

 Cope, in 1872, under the name Agathaumas,' which is now recognized by 

 botb paleontologists as belonging to the horned dinosaurs. This occurrence 

 does not, however, prove the extension of the Ceratops fauna downward 

 into Laramie strata equivalent to the Laramie of the Denver field, for the 

 Black Butte locality is one concerning which geologists have differed in 

 their observations, some thinking to have found evidence of a true break, 

 others not, and it is clear that much more field work in thai region is 

 necessary to harmonize the evidence of fossil plants, vertebrates, and the 

 published stratigraphic data. 



The dinosaurian horizon at Black Butte is above a line at which Major 

 Powell observed what he lias described as an important physical break 2 in 

 the series of 5,000 or 6,000 feet of strata assigned by others as a whole to 

 the Laramie. The saurian layer is also very near the top of the series and 

 is hence in the part which must correspond with the Arapahoe or Denver 

 in rase any subdivision of this section is earned through. The fossil flora 

 of Black Butte is neither distinctly Laramie nor Denver according to Mr. 

 Knowhon, having the intermediate character which might be expected of 

 the Arapahoe flora. The invertebrates of Black Butte are partly brackish 

 and partly fresh water forms. The former are known in other deposits 

 supposed to belong to the lower part of the Laramie, while the latter range 

 upward into post-Laramie and fort Union strata. It can only be said that 

 none of the lines of evidence is competent to satisfactorily decide the 

 position of the Black Unite deposits. 



Other Ceratops localities in Wyoming. Through tllC COlirtcSV of Ml'. J. I >. Hatcher 



the writer is able to state that representatives of the Ceratopsidae have 

 been discovered on the south side of the Seminole Mountains, and on 

 the west side of the North Platte River directly opposite the mouth of 



Medicine Bow Liver, Wyoming. This locality is 20 miles north of Fort 



Am. Nat., Vol. VI, 1872, p. 669. Proc. Acad. Nat. Sci., Phila., 1872, p.279. Proc. Am. Phil 

 XII. 1872, p. 181. 



i teology <>f tlie Uinta Mountains, p. 72, 



