1914] The Ottawa Naturalist. 151 



laterally in almost a horizontal plane. Its length is to its breadth 

 in tl oportion of about 7 to 8, with the maximum breadth 



near the posterior border. The parietal portion, which forms 

 more than half of the frill, is broadly triangular in shape with 

 the apex of the triangle in front. The squamosals are narrowly 

 triangular, broadest in front, and extend backward to within a 

 short distance of the crest's postero-lateral angulation. 



Within the coalesced parietals are two sub-triangular 

 fontanelles, longer than wide, and narrowing to the front, and 

 so large as to reduce the posterior two-thirds of the tals to 



a mere slender framework consisting of a median longitudinal 

 shaft, separating the openings, a transverse posterior bar en- 

 closing them behind, and narrow lateral bands forming their 

 outer margins. 



There are seven low, sub-conical epoccipitals on the lateral 

 free border of the right squamosal, eight apparently on the left, 

 and one, with a greater proportionate height, at each side of the 

 parietal portion on its postero-lateral angle. These separate 

 ossifications have a lengthened oval or lenticular basal outline, 

 the greater diameter being fore and aft, and the under surface 

 is excavated. They are in shape similar to the epoccipitals of 

 Triceratops and are applied to and cover the convexities of the 

 sinuous margin of the frill in a like manner. Of the series the 

 parietal one is the largest and there is a gradual diminution 

 in size forward. Of the five horned dinosaurs known from the 

 Belly River formation of Alberta, the present species and 

 Centrosaurus apertus only have epoccipitals. 



The parietals in advance of the fontanelles form a broad 

 surface, flat throughout, except along the median line, where 

 there is a low, rounded ridge which, becoming more pronounced 

 toward the front, terminates anteriorly in a small but well 

 defined upwardly inclined platform which reaches the level of 

 and effects a union with the postfrontals. This platform comes 

 to a sharp edge laterally, where it is undercut by the supra- 

 temporal fossae in a somewhat similar fashion as, but to a less 

 extent than, in Centrosaurus and Styracosaurus. 



The longitudinal parietal shaft is oval in cross section with 

 the greater diameter transverse. The posterior transverse bar 

 is bow-shaped, bending slightly backward on each side of the 

 median line and curving rapidly forward at each end to form the 

 postero-lateral angle of the frill. On its upper surface there is a 

 narrow ridge along the curved posterior border, and also a 

 similar thickening on the back margin of each fontanelle. The 

 main upper surface of the bar between the ridges is shallowly 

 excavated. 



