82 0. C. Marsh — New Dinosaurian Reptiles. 



The nasal horn-core is wanting in the present specimen, as 

 it was not ossified with the nasals. It projected upward and 

 forward. The nasal bones extend outside the superior branch 

 of the premaxillaries, the lateral suture uniting the two being 

 nearly vertical. 



The present specimen is from the Ceratops beds of Wyoming, 

 in essentially the same horizon of the Laramie as the skull of 

 Triceratops jlabellatus, to which reference has been made. 



Triceratops prorsus, sp. nov. 

 A second skull of this genus, fully adult, and of nearly equal 



dimensions, was secured at the same time as the specimen 

 last described. It is in excellent preservation, although some- 

 what distorted, and evidently belongs to a distinct species. 



The nasal horn-core and the rostra^ bone are in position, and 

 perfect. The former is very large, and is directed straight for- 

 ward, its upper surface being nearly on a line with the superior 

 face of the nasals. It is somewhat oval in transverse section ; 

 and pointed in front, the apex being directly above the anterior 

 extremity of the rostral bone. It is so firmly coossified with 

 the nazals that no trace of a suture can be observed. Its exter- 

 nal surface is rugose from vascular impressions, indicating that 

 it was covered by Jiorn, thus forming a most powerful weapon. 



The huge frontal horn- cores are more massive, and less 

 slender, than in the species above described. 



The parietal crest is not so broad as in the two species last 

 described, but appears to resemble more strongly that of 

 Triceratops horridus, its sides being inclined downward, as if 

 to protect the neck. 



The rostral bone, likewise, is very similar to that in the last 

 species, but is somewhat more compressed. The two forms 

 may be readily distinguished by the nasal horn-core, for in 

 T. horridus, this is comparatively small, and points directly 

 upward, instead of straight forward, as in the present species. 



With this skull were found several cervical vertebrae, and some 

 other portions of the skeleton. The atlas, axis, and third ver- 

 tebra are firmly anchylosed with each other, and their ribs, also, 

 are coossified in the same mass. This union, unknown hitherto 

 among the Dinosauria, was evidently rendered necessary to 

 afford a firm support for the enormous skull. The remaining 

 cervical vertebrae are short and massive, and the articular faces 

 of the centra are concave or nearly flat. 



The present specimen is from the Laramie of Wyoming, and 

 was found in the same vicinity as the skull above described. 



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