88 



THE CEEATOPSIA. 



and powerful horn. This is compressed and pointed, with the anterior margin acute and the 

 posterior rounded. It was straight and was directed upward and backward. Just in front 

 of the nasal horn there is on the inferior side of the nasals a median septum. The extremity 

 of this is broken away, so that it is impossible to determine its extent. The narial passage 

 is both wide and deep. The nasals are very narrow anteriorly, but wide posteriorly, where 

 they present an underlapping suture for contact with the frontals. Inferiorly and posteriorly 

 they present an underlapping plate which was overlapped by the premaxillary, and this articu- 

 lation is made more rigid by the median notch shown in the figure. The premaxillary is much 

 constricted medially but moderately expanded posteriorly for union with the nasals, while 

 anteriorly it is much expanded in order to give efficient support to the rostral, which is wanting 

 in the present specimen. Together with the nasals the premaxillaries on either side inclose 



Fig. 91. — A, Lateral view of nasal horn and beak of Monoclonius sphenocerus Cope, type, No. 3989, American Museum of Natural History; 

 B, front view of same; C, posterior view of same, h, Nasal horn core; n, nasals; fn, fronto-nasal suture; pmx, premaxillary. All one- 

 eighth natural size. 



a large heart-shaped foramen. The anterior extremities of both the nasals and premaxillary 

 are wanting in the present specimen. 



Principal measurements of the type (No. 3989). 



Mm. 



Estimated total length of nasals ' 505 



Greatest length of nasal horn core 302 



Transverse diameter of horn core at base. 80 



Antero-posterior diameter of horn core at base 160 



Height of apes of horn above premaxillary suture 465 



GENERA AND SPECIES OF CERATOPSIA FROM THE JUDITH RIVER BEDS OF CANADA, 



DESCRIBED BY LAMBE. 



Having concluded this review of the different species of Monoclonius that have been 

 proposed by Cope upon remains of these dinosaurs from the Judith River beds of northern 

 Montana, I will next consider the forms described by Prof. H. F. Osborn and Mr. Lawrence M. 

 Lambe and based, for the most part at least, on material collected by the latter in the Belly 

 River beds of the Northwest Territory, Canada. 



