96 THE CERATOPSIA 



tures found in Eoceratops. Contrasts with Eoceratops are found in the inclination of the postorbital 

 horns and the presence of epoccipitals, which are absent in Eocerato-ps. These are not significant points, 

 but the longitudinally-divided nasal horn core of Eoceratops type, as distinguished from that of the 

 present specimen, is of importance. In comparison with Chasmosaurus, the epoccipitals and the 

 parietal fenestrae agree, but Gilmore thinks the squamosal too short, even if continued beyond the 

 broken end. Our figure shows, however, that the squamosal could be prolonged to agree with 

 Chasmosaurus without lack of harmony with the preserved lines. With the rostral added, this skull 

 shows rather marked similarity with Chasmosaurus kaiseni. The muzzle is somewhat shorter, the 

 nasal horn differs, and the brow horns are not so long, but the character of the jugal and the 

 anterior margin of the squamosal defining the jugal notch are very similar, as well as the compara- 

 tively long brow horns. Gilmore's objection, on the ground of the small size of the skull, is hardly 

 valid, for the specimen seems to be nearly as large as the type of kaiseni. 



Dimensions 



(From Gilmore) 



Greatest length of skull, estimated about 1200 mm. 35 



Greatest width of squamosal 280 



Height of brow horn above superior border of orbit 170 



Antero-posterior diameter of horn at base 65 



Height of skull, from border of alveolus to tip of nasal horn, about 320 



My identification would place this as a variant, possibly sexual, of Chasmosaurus kaiseni. 



Genus CERATOPS Marsh 



This Judith River genus is based on so very inadequate material as to be undefinable. Four 

 species were described by Marsh, of which one, Ceratops paucidens, was based upon a left pre- 

 maxillary and maxillary with its contained teeth. This Hatcher determined to belong to one of 

 the trachodons, and hence not ceratopsian at all. Another skull described as Ceratops horridus, was 

 afterward made the type of a new genus Triceratops, while the third, Ceratops alticornis, con- 

 sisting of a pair of brow horns, from the Denver beds, was later removed to the genus Triceratops, 

 where it evidently belongs. Thus, only one is left, Ceratops montanus, which is the genoholotype. 



Ceratops montanus Marsh 36 



Holotype: No. 2411 U.S.N.M.; occipital condyle, and a pair of supraorbital horn cores. 



Horizon: Judith River formation. 



Locality: Cow Creek, about 10 miles above the confluence of that stream with the Missouri River, Montana. 



Collector: J. B. Hatcher, li 



In addition to this scanty material, Marsh referred the squamosal, No. 4802 U.S.N.M., to this 

 species, while another, No. 2415 U.S.N.M., was also figured in the Ceratopsia Monograph and 

 referred to C. tnontanus. 37 These are both short squamosals and might with equal, if not greater, 

 propriety, be referred to Monoclonius, for they are of the character of those borne by M. crassus, as 

 the short sutural surface in the type shows. They give no aid whatever in defining the genus 

 Ceratops, because of their lack of actual association with the type. The only known character, there- 

 fore, lies in the brow horns themselves, which, in the absence of other skull features, are insufficient 

 to define the genus. 



35 I. would estimate this at nearer 1 500 mm. 



3n Marsh, O. C, 1888, pp. 4-77-478. 



37 Hatcher, Marsh, Lull, 1907, PL HI, Figs. 1, 2. 



