122 THE CERATOPSIA 



The mandible seems rather slender for so deep a facial region of the skull. The 

 coronoid process is moderately expanded at the summit, and is not hook-like, as in Monoclonius 

 {Centrosaurus). 



The preorbital fossa was apparently entirely within the maxillary, although the depression was 

 bounded also by the lacrymal and jugal on the rear side and below, respectively. 



T. flabellatus is an isolated species, the affinities of which lie perhaps as near serratus as any 

 other. In these two, the jugals are the most similar, and while the nasal horn has been lost in 

 each instance, they may also have been alike. Proportions differ, for serratus is long and slender, 

 viewed laterally, while flabellatus is deep. This, as well as the bosses on the horn base and 

 squamosal of serratus, may be an age distinction. The dorsal profiles are, in general, alike, except 

 for the prominences along the midline of the crest in serratus. The flabellatus skull is smooth 

 throughout, lacking the vascular impressions so well marked in serratus, but this is a matter of age. 

 T. serratus also stands alone except for this suggested affinity. Finally, they were found very near 

 each other, although the flabellatus comes from a slightly higher level. 



Triceratops elatus Marsh 74 



Holotype: 75 No. 1201 U.S.N.M.; skull. 

 Horizon: Lance formation, No. 12 in the sequence. 

 Locality: Niobrara County, Wyoming. 

 Collector: J. B. Hatcher, 1890. 



This specimen represents a somewhat immature animal of average size, the skull measuring 

 6 feet 2^4 inches in length. The dorsal profile of the skull is distinctive, the facial portion having 

 a decided hollow curve straightening out toward the cranium proper, which is the highest point, 

 except for the extreme rear of the crest ; in this it resembles Triceratops calicornis, its nearest rela- 

 tive. The muzzle is rather slender and of moderate length, although the rostral is fairly large. 

 The latter has deep vascular grooves and a comparatively straight inferior margin which points 

 decidedly downward toward the tip. The narial opening is very large. The nasal horn is peculiar, 

 although resembling that of calicornis more than any other species in having the dorsal margin 

 slightly below and not continuous with that of the nasals. The horn core, while bearing vascular 

 impressions, is truncated, the anterior and superior margins being at right angles with each other, 

 the former overhanging the base of the muzzle and inclining slightly backward. 



The brow horns are long and massive, extremely heavy at the base where they are strongly 

 compressed laterally, becoming more circular in section toward the tip. The rear of the base bears 

 a marked prominence, as in calicornis, obtusus, and serratus. The horn curves strongly forward, 

 reversing slightly toward the extreme tip. 



The orbit is a broad oval of regular outline, with the broader end uppermost, and inclines at 

 an angle of about 15° out of the perpendicular. The jugal is unique in that it is ""[-shaped, having 

 no posterior limb, as in every other ceratopsian skull, the posterior margin being continuous with a 

 somewhat irregular suture which extends directly upward and forward to the orbit. Skull No. 2 1 00, 76 

 on the mounted skeleton in Washington, is suggestive of elatus in this, as in certain other features, 

 but the jugal is broader. The descending limb is long and rather narrow, with curved, nearly 

 parallel front and rear margins. The longitudinal ridge, which is but slightly developed, lies near 

 the rear instead of being in the center of the bone. The jugal notch is deep and wide, and the 

 infratemporal fossa unusually large and triangular, with the apex pointing toward the orbit. 

 Unfortunately, the jugal complex is visible only on the left, and, as the bone seems abnormal, one 

 would like to compare it with that of the other side were it possible. 



74 Marsh, O. C, 1891, p. 265. 



75 Hatcher, Marsh, Lull, 1907, PI. XLIII. 



76 Hatcher, Marsh, Lull, 1907, PI. XXX. 



