TRICERATOPS CALICORNIS 123 



The crest is of average size and curves strongly upward toward the rear, the dorsal profile 

 being only slightly undulating. The epoccipitals and epijugals are lacking. They were originally 

 present, however, the former numbering about 21. The squamosal is very wide, especially at its 

 mid length, but has much the same general form as in calicomis. The area of the crest lying about 

 the supratemporal fossa, especially toward its rear, is deeply excavated and evidently pathologic. 

 Otherwise, the sculpturing, especially of the vascular grooves, is not so very marked on either surface 

 of the crest, above or below. 



To the species elatus may also be referred the skull No. 21 00 U.S.N. M., at present associated 

 with the mounted skeleton at Washington. This fine skull is complete, except for the muzzle, 

 which has been restored. Its dimensions are about those of the elatus type, the over-all length being 

 6 feet 3 1 j inches for No. 2100 U.S.N.M., and 6 feet 2->4 inches for elatus. The small nasal horn 

 is like that of elatus with its dorsal surface depressed below the level of the nasal bones. The brow 

 horns, on the other hand, differ in their angulation, being strongly anteroverted, with a reversed 

 curve toward the tip, and in the form of the basal section which is nearly circular. The orbit is also 

 nearly circular, in contrast to its elliptical form in elatus. The epijugal has a high ridge, and the 

 jugal itself is broad, with a limited posterior limb, resembling somewhat the peculiar jugal of elatus. 

 One marked peculiarity which resembles prorsus and brevicornus, rather than elatus and calicomis, 

 is the limited peripheral zone of vascular impressions on the under side of the crest which, in 

 this instance, seems correlated with an outward and upward flare of its margin. The maxillary 

 teeth number 28 vertical rows. The affinities of this skull lie clearly with Triceratofs elatus Marsh, 

 the only discordant feature being the peripheral zone of vascular impressions on the under side of 

 the crest. 



Yet another skull of somewhat doubtful affinity, but nearer elatus perhaps than any other, is 

 that on the mounted skeleton 77 of Triceratofs in the American Museum of Natural History. This 

 mount (PI. XIV, A) is composite, the skull, No. 5116, having been collected by C. H. Sternberg 

 in Weston County, Wyoming, while the skeleton, No. 5033, No. 5039, No. 5045, was collected by 

 Brown and Kaisen in 1909 in the Hell Creek region in Montana. This is a large skull, 6 feet 

 iy 2 inches, of an adult but not an aged individual, as the sutures are still very clearly defined. In 

 general proportions, it differs from elatus in being relatively shallow for its length, especially in the 

 cranial region, and in the enormous crest which is smooth above and below and has an even margin, 

 without epoccipitals in its present condition, although doubtless the usual number was originally 

 present. The muzzle has the proportions of elatus rather than of calicomis, with a large narial 

 opening. The nasal horn is rather larger than usual, but shows the depression of the dorsal contour 

 slightly below that of the nasals. The brow horns are enormous, strongly anteroverted, as in 

 No. 2100 U.S.N. M., but almost straight beyond the base, which is circular in cross section. The 

 tips extend almost to the anterior limit of the premaxillaries. All of the horns have deep vascular 

 impressions. The orbit is nearly circular, as in No. 2100 U.S.N.M., while the jugal is rather 

 narrow, tapering and raking backward rather more than usual. The jugal notch is very shallow, 

 but the infratemporal fossa is relatively larger than in the elatus type, almost semi-circular in form, 

 with the upper margin nearly straight. This skull evidently belongs to the elatus-calicomis phylum, 

 but of its strict specific identity with elatus one cannot be sure. There is infinite variation in all 

 Triceratofs skulls. 



Triceratops calicomis Marsh 7 * 



Holotype: 78 No. 4928 U.S.N.M.; skull and portion of skeleton. 

 Horizon: Lance formation, No. 17 in the sequence. 

 Locality: Niobrara County, Wyoming. 

 Collector: J. B. Hatcher, 1889. 



77 Osborn, H. F., 193 3. 



78 Marsh, O. C, 1898, p. 92. 



"Hatcher, Marsh, Lull, 1907, Pis. XXXV1II-XXXIX. 



