TRICERATOPS ELATUS. 135 



LOCALITY. 



The type (No. 1201, U. S. National Museum) of the present species was found by the 

 writer in a loose bed of arenaceous shale on the east side of Lance Creek. It lay on the gently 

 sloping hillside, about a quarter of a mile from the creek and directly opposite the mouth of 

 Lightning Creek. The locality is shown at + 16, in PL LI. The horizon I should judge to be 

 about the middle of the Laramie series, although owing to the absence of exposures of either 

 the underlying or overlying deposits in this immediate vicinity it is difficult to determine exact 

 horizons with even moderate precision, and this difficulty is augmented by the frequency with 

 which the sandstones and shales of these deposits replace one another, both vertically and 

 laterally, making it extremely difficult to trace any given stratum for any considerable dis- 

 tance. Immediately in front and removed about 8 feet from the skull on the same horizon 

 was the lower jaw shown in fig. 114. This may have belonged to the type, although fragments 

 of another skull were found dying about at the same locality. 



ORIGINAL DESCRIPTION. 



Professor Marsh's original description of this species was as follows: 



One of the largest members of the Ceratopsidae, representing a distinct species, is at present known from the skull only, 

 which was procured during the past year. Although this skull is about 6 J feet in length, it belonged to an animal scarcely 

 adult, as indicated by some of the cranial sutures. The rostral bone is not coossified with the premaxillaries as in old 

 animals, and the superior branch of the former bone has its extremity free. The nasal horn core, however, is firmly coossified 

 with the nasals. It is of moderate size, with an obtuse summit directed upward. The main horn cores were quite long, with 

 their extremities pointed and directed well forward. These horn cores are compressed transversely, the section being oval 

 in outline. 



One of the most striking features of the skull is the parietal crest, which was quite elongate and much elevated, 

 more so than in any of the species hitherto discovered, and this has suggested the specific name. 



The length of this skull from the front of the rostral bone to the back of the parietal crest was about 78 inches, 

 and the greatest transverse expanse of the posterior crest was about 40 inches. The summit of one of the frontal horn cores 

 was about 28 inches above the orbit and 53 inches from the base of the quadrate. 



This interesting specimen was found in the Ceratops beds of the. Laramie in Wyoming by Mr. J. B. Hatcher, of the 

 U. S. Geological Survey, whose previous discoveries are well known. 



SPECIFIC FEATURES. 



The type consists of a very complete left side of a skull, showing all the more important 

 cranial characters. When found it lay on its left side, and the upper or right side had weathered 

 away. 



The anterior portion of the skull and the left half of the middle and posterior regions 

 are exceptionally well preserved, making it possible to determine most of the more important 

 cranial characters, and these are well shown in PL XLIII. 



The most striking specific characters are to be seen in the nasal and supraorbital horn 

 cores and the jugal, as will appear from comparison of the figures of the type of the present 

 species with those of the other species of Ceratopsia found in the Laramie. The orbit also 

 is exceptionally large, having a vertical diameter of 175 mm. and an antero-posterior diameter 

 of 150 mm. The infratemporal fossa is much elongated antero-posteriorly and is triangular 

 in outline. Its greatest antero-posterior diameter measures 145 mm. and its greatest vertical 

 diameter has a length of 85 mm. 



Epoccipitals were borne only on the posterior margins of the parietals and the posterior 

 half of the squamosals. The antero-external border of that portion of squamosal back of the 

 groove for the quadrate is rather sharp edged, regular in outline, and presents neither that 

 series of undulations noticed in several other species of the Ceratopsia nor surfaces for the sup- 

 port of epoccipitals. Each squamosal supported four epoccipitals, and there were six on the 

 parietals, three on either side of the median line. Apparently there was no median epoccipital 

 as in T. prorsus and other species. 



The supraorbital Jiorn core is long and massive and curves strongly forward. Throughout 

 most of its length it is much compressed laterally, but at the extremity it is subcircular in 

 outline. 



