TRICERATOPS BREVICORNUS. 141 



I have been unable to find in the collections of the U. S. National Museum the squamosal 



mentioned by Marsh as pertaining to the type, and hence can say nothing concerning the form 



of this important element. The other portions of the skeleton preserved show no peculiarities 



worthy of note. 



Triceratops brevicornus Hatcher. 



Type (No. 1834, Yale Museum) from Laramie of Converse County, Wyo. 



Original description in Am. Jour. Sci., 4th ser., vol. 20, p. 413. 



Char, specif. — Supraorbital horn cores short and stout, not much compressed, nearly circular in cross section. Nasal 

 horn core short and stout with the anterior border perpendicular instead of being directed upward and forward at an 

 angle of 30°. Vertical and longitudinal diameters of lateral temporal foramen nearly equal. Orbit irregularly elliptical 

 in outline with the longer axis running from above downward and forward. Postfrontal fontanelle open, even in old 

 individuals. 



The type (No. 1834, Yale Museum) of the present species consists of a nearly perfect skull 

 with lower jaw and a complete series of presacral vertebras, together with a number of ribs 

 more or less complete, and portions of the pelvis, including a portion of the right ilium and 

 a nearly complete pubis. 



LOCALITY AND HORIZON. 



The skeleton was discovered by Mr. W. H. Utterback, and the exact locality was about 

 3 miles above the mouth of Lightning Creek and about 1^ miles south of that stream, in Converse 

 County, Wyoming. The locality is indicated by + 22, in PI. LI. The horizon was near the 

 summit of the Laramie, and the specimen was collected by the present writer assisted by Messrs. 

 W. H. Utterback, A. L. Sullins, and T. A. Bostwick. When discovered the skeleton lay embedded 

 in a hard sandstone concretion and was much shattered and weathered about the pelvic region. 

 The vertebral series lay in position with the vertebrae interlocked by their zygapophyses from 

 the axis to the last dorsal, though portions of some of the vertebras had weathered away when 

 found. Behind the posterior dorsal, impressions of the centra of the first two sacrals were 

 preserved in the hard sandstone in which the skeleton was embedded. None of the limb bones 

 and no part of the tail were recovered. 



DESCRIPTION OF TYPE. 



THE SKULL. 



The extremely rugose nature of the skull, together with the closed condition of the sutures, 

 many of which are almost or entirely obliterated, make it certain that the type of the present 

 species pertained to an old individual. 



The cranium. — The chief distinctive features of the cranium are as follows: The supra- 

 orbital horn cores are unusually short and stout, especially at the base. They are less com- 

 pressed and more nearly circular in cross section than in most other species. The nasal horn 

 is short and very stout, the antero-posterior diameter much exceeding the transverse. Its 

 anterior border is directed upward in a line perpendicular with the longer axis of the skull 

 instead of forward and upward at an angle of about 30° to that axis as in the type of T. prorsus. 

 The lachrymal foramen, as in T. serratus, lies between the maxillary and the nasal, but in 

 the present species its anterior half is entirely inclosed by the maxillary, that bone sending 

 upward a short process alongside the premaxillary process and forming the anterior one-half 

 of the superior border of the foramen. The orbit is elliptical in outline, the longer diameter 

 being inclined backward from the perpendicular at an angle of about 10°. The lateral temporal 

 fossa is triangular in outline, its respective borders describing nearly an equilateral triangle, 

 the fore-and-aft diameter only slightly exceeding the vertical. The rostral bone is heavy 

 and very deeply excavated beneath. The epijugal is rather acutely pointed and regularly 

 triangular in cross section. The infratemporal arch, as in T. serratus, is formed by the quadrate 

 with overlapping processes from the jugal and squamosal, that from the latter element occupying 

 a slightly more elevated position in the type of the present species than in that of T. serratus. 

 The exoccipital process extends distally beyond the quadrate and projects as a small angular 

 process. There are six epoccipitals, borne wholly on the squamosal, and at least three more 

 between the last of these and the single median one situated at the median parietal region. 

 Though the frill is not sufficiently perfect in this region to determine the number of epoccipitals 



