174 THE CEEATOPSIA. 



TOROSAURUS. 



1. Torosaurus latus Marsh (pp. 150-152, fig. 118) is based upon a specimen (No. 1830, 

 Yale Museum) consisting of an incomplete skull of an aged individual. 



Nasal horn core broad at base, sharp above, directed upward and forward. Supraorbital 

 horn cores much compressed, ovate, with apex forward. Horn cores directed upward and out- 

 ward and forward. 



Supratemporal fossae relatively larger than in T. gladius. 



Skull b±oad and massive between the orbits. Parietal fontanelles not entirely within the 

 parietals, in contrast to those of T. gladius. Hatcher says that he can not verify this feature in 

 latus. 



The postfrontal fontanelle paired, as opposed to single median one in T. gladius. 



2. Torosaurus gladius Marsh (pp. 152-155, figs. 7, 12, 14, and 119) is based upon a type 

 specimen (No. 1831, Yale Museum) consisting of detached portions of a skull. 



Nasal horn core very short, stout, compressed, with a sharp apex. It is very rugose, the 

 section being an oval with the rounded portion in front. 



The supraorbital horn cores are rather long, slender, somewhat compressed laterally, and 

 very rugose. They were directed forward and outward. 



The postfrontal fontanelle seems to have been single, as opposed to the paired ones in 

 T. latus, but the broken condition of the skull in this region leaves this point somewhat in doubt. 



The supratemporal fossae are proportionately smaller than in T. latus, and the fontanelles 

 are entirely surrounded by the parietal bones. 



Hatcher says : ' ' The type of the present species represents the extreme development of the 

 form of parietal crest that is peculiar to this genus," though T. gladius is geologically the older 

 of the two species. 



GEOLOGY AjNTD PHYSIOGRAPHY OF THE VARIOUS CERATOPSIA LOCALITIES. a 



The remains of Ceratopsia, though referred by various authors to each of several horizons, 

 are referable either to the Judith River of Montana and its equivalent, the Belly River of Canada, 

 or to the Laramie of Wyoming and Montana and the Denver and Arapahoe formations of 

 Colorado. 



The principal geographical localities, as well as one or two minor places from which 

 Ceratopsia remains have been reported, are shown on the accompanying map (PI. L). 



The vertical range of the Ceratopsia is limited to the upper half of the upper Cretaceous. 



JUDITH RIVER LOCALITIES OF MONTANA. 

 CORRELATION. 



The conclusions reached by Messrs. T. W. Stanton and J. B. Hatcher h concerning the 

 stratigraphic position of the Judith River beds and their correlation with the Belly River forma- 

 tion are of prime importance in considering the phylogeny of the Ceratopsia. These general 

 conclusions, based upon a careful resurvey of the upper Cretaceous formations in Montana and 

 the adjacent parts of Canada having special bearing upon the problems in hand, are as follows: 



1. The Judith River beds are distinctly older than the Laramie, being separated from the latter by at least several 

 hundred feet of marine shales, identical in their faunal and lithologic features with the Pierre, to which we have given the 

 local name of Bearpaw shales, from the Bearpaw Mountains, about which they are well exposed. 



/ 2. The Belly River beds of Canada are identical with the Judith River beds of Montana. The name Judith River beds 

 having priority should be the accepted name for this formation, and the terms Belly River and Fish Creek beds should be 

 dropped. 



3. The marine sandstones and shales immediately underlying the Judith River beds do not represent either the Benton, 

 as some Canadian geologists have supposed, or the Fox Hills and upper Pierre, as most geologists of the United States who 



a Based upon the writings of Hatcher, Stanton, Lambe, Eldridge, Cross, and upon the writer's own explorations. 

 b Geology and paleontology of the Judith River beds: Bull. U. S. Geol. Survey No. 257, p. 66, 1905. 



