36 
long and slender; brow horns rising moderately far apart, circular in cross- 
section, and pointing forward, upward, and slightly outward; fontanelles of 
moderate size and oval in outline; crest moderately thin. 
The skull is apparently that of an old individual, as all the sutures are 
thoroughly closed by co-ossification of the different bones. The more 
slender proportions and thinness of the crest can not, therefore, be regarded 
as juvenile characters. 
When viewed from the side (Plate XXI), the skull is very long and 
flat, the orbit is well in advance of the midline; the anterior naris is long 
and situated nearer to the orbit than to the end of the beak. The nose, in 
front of the nasal horn core, is very long and slender, being relatively 
longer than in any other species known to the writer. The rostral bone 
resembles that of Chasmosaurus 1 and as in that genus the beak is made up 
largely of the pre maxillae, whereas in Arrhinoceratops Parks 2 shows the 
rostral extending back to the nasal horn core. The beak at the deepest 
point is less than two-thirds as deep as it is long. 
The nasal horn core resembles that of Arrhinoceratops br achy ops. 
It is triangular in cross-section with the apex of the triangle above, and it 
points forward and upward. Vascular grooves are not so well developed 
as on the brow horns, but there is no doubt it carried a fair-sized horny 
sheath. An epinasal is not discernible, but this would hardly be expected 
in an old animal. Parks states that Arrhinoceratops does not have a nasal 
horn core, but his illustration shows one. He evidently has reference to 
the epinasal, for he states later that the nasal bone may have carried a 
horny sheath. In all of the Belly River Ceratopsia the nasal horn core is 
made up principally or solely of the nasal bones. In some Belly River 
forms, young individuals show a separate ossification in front of, or on the 
tip of, the nasal bones, and this has been called the epinasal. In some 
species of Triceratops the epinasal constitutes the nasal horn core, whereas 
in others the nasal bones play a very important part in its formation. 
There seems little doubt that in all of the earlier forms the nasal horn core 
was composed mainly of the nasal bones. 
The orbit is moderately large and circular in outline. The centre of 
the orbit is 650 mm. from the anterior end of the beak and 1,020 mm. from 
the posterior edge of the crest. 
The brow horn cores, which are developments of the postorbital bones, 
are moderately large and circular in cross-section, except at the base where 
they are sub-triangular. They rise from the supero-posterior border of 
the orbits and continue upward, forward, and slightly outward, thus 
differing from A. ornatus in which they curve outward, then forward. 
They taper gradually to the tip, but are farther apart at the base and much 
smaller than those of A. ornatus. The horn cores bear well-defined, 
longitudinal, vascular grooves. There is a slight flattening on the external 
and posterior sides at the base of the horn core, thus giving a somewhat 
triangular cross-section there. 
The frontal fontanelle is closed superiorly, due to the union of the 
frontals, thus completing the secondary roof on the superior surface. 
This frontal fontanelle opens posteriorly, however, and, apparently, is 
1 See Lambe, L. M.: Geol. Surv., Canada, Mus. Bull. No. 12, PI. VIII (1915). 
* Loc. cit., PI. II R. 
