166 THE CERATOPSIA. 



orbitals are larger than in Ceratops. The orbits are elliptical, with the long diameter more 

 nearly horizontal than in other genera, and are placed farther forward relative to the position 

 of the horns than in Triceratops, while the skull is broad and massive between them, narrowing 

 very rapidly toward the snout. The skull is extremely broad in the region beneath the orbits, 

 as the external surface slopes downward and outward as compared with the more nearly verti- 

 cal sides of the skulls referable to the genus Triceratops. There is a large lachrymal foramen 

 well in advance of the orbit. 



The postfrontal fontanelle seems to have been paired, at least in T. lotus, the type of T. 

 gladius being too imperfect to permit one to judge. From this run two shallow grooves 

 directed outward and backward, each ending in a small foramen. There are similar grooves 

 in the type of Diceratops, and in the specimen (Nos. 1203 and 1206-1210, U. S. National 

 Museum) referred by Marsh to Triceratops sulcatus (PI. XXXVII, fig. 1) the grooves are present 

 but as the posterior portion of the skull is broken away the terminal foramina can not be seen. 

 In each of these forms, however, the postfrontal foramen is unpaired. 



The parietals are broad and long, with large supratemporal fontanelles. The parietal 

 fontanelles are not so large proportionately as in Ceratops, and the median bar is broad, thin, 

 and smooth, especially toward its posterior end. The squamosals are very elongate and sword- 

 like, readily derivable from such as are found in Ceratops. The quadratojugal notch is much 

 less pronounced than in Triceratops; the groove for the quadrate being far in advance of its 

 position in other genera. The posterior margin of the frill is emarginate, but there are no 

 separately ossified epoccipitals as in Triceratops. 



III. GENERA ELIMINATED OR REMOVED FROM THE CERATOPSIA. 



The genera abandoned or removed from the Ceratopsia by Hatcher are named below: 



1. ClaorhyncJius Cope, with its one species, trihedrus, founded upon a rostral and pre- 

 dentary bone, and now lost sight of, Hatcher supposes, from Cope's description, to pertain to the 

 Trachodontidse rather than to the Ceratopsia. 



2. Dysganus Cope, with its four species, D. encaustis, D. Tiaydenianus, D. bicarinatus, and 

 D. peiganus, is abandoned on the ground that it was "based on teeth pertaining to two or more 

 genera belonging in part to the Trachodontidse and in part to the Ceratopsidae." The type 

 material was very imperfect and the descriptions were inexact and unaccompanied by figures, 

 hence the genus should, in Hatcher's opinion, be considered a nomen nudum. 



3. Manospondylus Cope, with its single species, gigas, is based upon the centrum of a single 

 vertebra (fig. 105). From its general form, its coarsely cancellated internal structure, and the 

 deep fossa of the superior lateral surface it resembles most closely the vertebra? of Dryptosaurus, 

 a theropod dinosaur, hence one is justified in removing the genus in question from the Cera- 

 topsia. 



4. Another of Cope's genera, Polyonax, with the species mortuarius, erected upon "frag- 

 ments of horn cores, vertebra?, etc.," is abandoned because of "the extremely fragmentary and 

 totally inadequate nature of the material upon which the genus and species are based." 



5. Finally, Lambe's genus Stegoceras, with its single species, validus, is based upon two 

 cranial fragments (figs. 99 and 100 and PI. XXII), which Lambe called "prenasals," but which 

 Hatcher believed are the "superior portion of the occipital, parietal, and frontal segments of 

 the skull" of a reptile which may represent an order new to science. He further adds that 

 "there is no good reason for considering them as horn bearing or the animals to which they 

 belonged as pertaining to the Ceratopsia." Hence Hatcher does not include the genus in that 

 group. 



6. Sterrholophus Marsh is considered synonymous with Triceratops, for the reasons already 

 mentioned. 



