102 THE CERATOPSIA 



total length of the animal from the end of the nose to the tip of the tail is about 6 feet 9 inches, 

 and its height at the hips, about 2 feet 4 inches. The number of presacral vertebrae was made to 

 correspond with that of Triceratops brevicornus type, at that time the only complete presacral series 

 known. As interpreted by Gilmore, this number was 22, as he seemingly followed Lull in inter- 

 preting the number of coalesced (anterior) cervicals as four, instead of the generally accepted three. 

 The number should be 21, cervicals 7-9, and dorsals 14-12, according as one interprets numbers 8 

 and 9. The number of sacrals is given as 6, and caudals as 50, making 78 in all, according to 

 Gilmore, or 77 with the corrected number of cervicals. This is exactly the same total as in Mono- 

 clonius (Centrosaurus), the latter having 4 more sacrals and 4 fewer caudals, which again may be 

 merely a matter of greater maturity. 



Brachyceratops once more has but a single species montanensis, so that the specific characters, 

 as distinguished from the generic, are not definable, especially in light of the juvenile state of the 

 only known material. 



The relationship of Brachyceratops with other genera is obscure. The form of the squamosal — 

 of highly diagnostic value in the Ceratopsia — places it nearest to Monoclonius, but Gilmore makes 

 the following points of contrast. He says that Brachyceratops has no epoccipital bones around the 

 margin of the crest. However, this is negative evidence and should be evaluated as such, for at the 

 ontogenetic stage represented by the type material they would not be coossified, and hence would be 

 readily lost; and they may have been very much smaller than in a mature animal. He says also 

 that there are no hook-like processes on the posterior border of the parietals, but the anterior pair of 

 these is variable in occurrence and even the rear ones — invariably present in all known Centro- 

 saurus species— are missing in the generic type, Monoclonius crassus. The fenestrae of the crest are 

 decidedly smaller than in Monoclonius, but this again may be expected in a somewhat later phylo- 

 genetic stage. The real distinction lies in the longitudinally divided nasal horn which is apparently 

 unique except for Eoceratops canadensis Lambe from the Belly River formation. Here, however, 

 there is what has been called an epinasal on the anterior face of the nasal horn which finds no 

 parallel in Brachyceratops, unless the small terminal ossicle which Gilmore figures as capping the 

 left of the paired bones is its homologue. The brow horns in the two genera are totally different. 

 The species Monoclonius dawsoni Lambe has been referred to Brachyceratops by Lambe 50 but on 

 insufficient evidence, for the nasal horn is a large backwardly curved element without trace of 

 division into right and left halves except at its base and for a short distance upward into the horn 

 core. The other characters stressed by Lambe are the incipient supraorbital horn cores, small squa- 

 mosal, smooth undulating border to the crest without epoccipitals, and greatly reduced openings in 

 the parietals, if they were present at all. The type of dawsoni was so ill preserved that it was not 

 all collected, and one has to depend upon Lambe's field sketch and personal description for the char- 

 acter of the crest. It is, in other words, impossible to verify the specific description from the present 

 condition of the type, and its inclusion in the genus Brachyceratops is therefore unprovable. 



Genus Anchiceratops Brown 



The most distinctive generic characters of Anchiceratops (PI. X) lie in the crest, which is rec- 

 tangular in form, with rather small fenestrae as compared with the area of the crest. Around the 

 rear margin are very large epoccipitals, six borne on the parietal, and on the squamosals a large 

 posterior pair with others of the usual form and size. The squamosals are long, but do not come so 

 near the end of the crest as is usual in Chasmosaurus. The latter also differs from Anchiceratops in 

 the much larger parietal fenestrae. In addition to the epoccipitals, there is a smaller pair of promi- 

 nences arising from the midline at the rear of the parietals and diverging outward. Brown describes 

 these as knob-like, but they are somewhat flattened and curved so as to be convex upward. The 

 degree of development of the horns is what one finds in all genera of this and succeeding geological 

 levels, namely, large, curved brow horns and a much smaller nasal horn. 



60 Lambe, L. M., 1915, pp. 6-7. 



