Triceratops serratus, sp. nov. First in importance of the new discoveries is a nearly perfect skull of the genus Triceratops, a typical example of which (T. flabellatus) was described and figured by the writer in the last number of this Journal.* The present skull is more perfect than any hitherto found, and exhibits admirably the strongly marked characters of the genus. It is likewise of gigantic size, being nearly six feet in length (l.8m), although the animal was not fully adult. A striking peculiarity of this skull, which has suggested the specific name, is a series of bony projections on the median line of the parietal crest. The latter is elevated along this line to support them, and the sides descend rapidly to their union with the squamosals. There is a second series of elevations along the middle of the squamosal bone as it falls away from the base of the horn-core, but these are much less prominent. The orbit is nearly circular in form, instead of oval, and is situated above, and forward of its position in the species referred to. The quadrato-jugal meets the anterior process of the squamosal, forming a closer union than in the skull previously figured. In this respect, and in the elevations on the squamosal, it approaches a much smaller specimen at present referred to the genus Ceratops. *This Journal, vol. xxxviii, pp. 501-506, December, 1889. 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 flabellatus, to which reference has been made.

Published as part of Marsh, O. C., 1890, Description of new dinosaurian reptiles, pp. 81-87 in American Journal of Science 39 (229) on pages 81-82, DOI: 10.5281/zenodo.3375239