* I Upper beds. 



CERATOPSIA LOCALITIES. 179 



The specimens representing the species of Ceratopsia may be placed with regard to their horizons as follows : 



Cat. No. 971, Centrosaurus apertus - I Lower beds 



Cat. No. 1254, Monoclonius canadensis J 



Cat. No. 1173, Monoclonius dawsoni Middle beds. 



(These beds should possibly be included with the upper beds.) 



Cat. No. 491, Monoclonius belli . 



Cat. Nos. 515, 1423, etc., Stegoceras validus 



The types, as regards their geographical position, are as follows: 



971 (Centrosaurus apertus). West side of Red Deer River, July 26, 1901. Not far from it were remains of Trionyx 

 foveatus, Leidy. 



1254a, etc. (Monoclonius canadensis). East side of Red Deer River, August 2, 3, and 20, 1901. At same level and near 

 remains of Trachodon. 



1173 (Monoclonius dawsoni). East side Red Deer River, August 15, 1901. 



491 (Monoclonius belli). East side Red Deer River, below the mouth of Berry Creek, August 13, 1898. Not far distant 

 and at the same level were found remains of Trachodon, Cimoliasaurus, and turtles. 



515 (Stegoceras validus). East side Red Deer River, below the mouth of Berry Creek, August 15, 1898; 1423, east side, 

 August 24, 1901. At about the same level as M . belli, Orniihomimus altus, Adocus variolosus, Ba'ena antiqua, Trionyx foveatus,. 

 etc., Ptilodus primsevus, Myledaphus bipartites, Lepidotus occidentalis, Diphyodus longirostris, etc. 



There seem to be no very distinct lithological differences on which to base these subdivisions of the Red Deer River rocks, 

 but the lowermost beds seen in the area below the mouth of Berry Creek include some yellowish sandstones, which may be 

 the uppermost beds of Doctor Dawson's lower yellow portion. 



LOCALITIES FOR LARAMIE CERATOPSIA. 



The main localities for Laramie Ceratopsia are three in number — one near Black Buttes 

 station on the Union Pacific Railroad, in southwestern Wyoming; a second, by far the most 

 notable, in the northeastern part of Converse County, Wyo., in the area shown on the map 

 (PI. LI), and a third in the canyon of Hell Creek, Montana, a tributary of the Missouri, about 

 135 miles northwest of Miles City. 



THE BLACK BUTTES, WYOMING, LOCALITY. 



The Black Buttes locality is interesting historically as having produced one of the first 

 specimens of ceratopsians, the type specimen of Agathauraas sylvestris Cope. It lies in Sweet- 

 water County, in southwestern Wyoming, not far from Black Buttes station on the Union 

 Pacific Railroad. 



Stanton and Knowlton" describe this locality as follows: 



The most prominent feature of the section at Black Buttes is the massive bed of sandstone, somewhat over 100 feet thick 

 at the base of the exposure, forming steep hills and cliffs northeast of the railroad opposite the station and passing beneath 

 the surface by its dip of 9° or 10° near the coal mine. * * * The original specimen of Agathaumas sylvestris was found 

 about 20 feet above it. 



The bones were found, according to Cope, in a bed of sandstone that lies just above the 

 lower stratum of the Bitter Creek series of coals and is overlain by two other coal seams. This 

 bed of sandstone "crops out high on the bluffs" a half mile east of the station. 



From the molluscan fauna it is judged that the beds below and above the dinosaur bed 

 consisted mainly of deposits from brackish water, with alternations of fresh-water deposits and 

 of coal seams, probably implying coastal swamps with abundant vegetation in which frequent 

 slight changes of level occurred, bringing in brackish waters during periods of subsidence and 

 fresh waters during periods of elevation. This would produce physical conditions in keeping 

 with our conception of the environment of the Ceratopsia. (See p. 194.) 



THE CONVERSE COUNTY, WYO., LOCALITY. 



The history of the discovery by Mr. Hatcher of this, the most important Ceratopsia locality, 

 has already been stated (pp. 7-9), and a description of the location and character of the deposits 

 is given in an earlier paper by Hatcher (Am. Jour. Sci., 3d ser., vol. 45, Feb., 1893, pp. 135-144), 

 from which I shall quote at length. The beds were reached by Hatcher by going north from 

 the town of Lusk, Wyo., on the Fremont, Elkhorn and Missouri Valley Railroad; now they 



a Bull. Geol. Soc. America, vol. 8, p. 143. (See also pp. 105-106.) 



