26 THE ROYAL SOCIETY OF CANADA 



preserved only in their upper part. A very small fragment in place 

 (plate I, pasp) apparently represents all that is left of the para- 

 sphenoid. 



Measurements of skull of Stegoceras, Cat. No. 138. 



Mm. 



Length from middle of posterior border to fronto-nasal suture 95 



Breadth at squamoso-postorbital suture 94 



Breadth at orbits 84 



Breadth of coalesced parietals between supratemporal fossae 2>2> 



Distance from lateral border to supratemporal fossa 24 



Depth (thickness of bone) of posterior border at midbreadth 14 



Thickness of bone at fronto-nasal suture 14 



Thickness of bone from roof of brain-cavity to top of parieto-frontal elevation . . 34 

 Length of brain-cavity from roof of foramen magnum to anterior end (position of 



olfactory lobes) 48 



Length of anterior chamber of brain-cavity (position of olfactory peduncles and 



lobes) 14 



Maximum breadth of roof of same 15 



Length of main chamber of brain-cavity 30 



Maximum width of same 20 



Distance apart of squamosal sockets for head of quadrate 63 



Breadth (transverse) of roof of orbit 31 



Parietals and frontals. These elements are large and coalesced 

 into a strong mass of bone which, owing to its thickness and solidity, 

 is the form in which recognized remains of this reptile are most fre- 

 quently preserved in the beds of the Belly River formation. A number 

 of the specimens, those consisting of the united parietals and frontals, 

 are more or less worn as if they had been rolled by water action, and 

 present much the same appearance as those originally described by 

 the writer in 1902. 



In the parieto-frontal mass (plate I) the union of the parietals 

 with the frontals is indicated by a transverse suturai line across the 

 roof of the brain-cavity at about the midlength of the specimen giving 

 the parietal contribution to the mass a length about equal to that 

 of the frontals. The parietal portion is broadest at the parieto- 

 frontal suture and narrows slightly backward to the supratemporal 

 fossa, and then more rapidly to the posterior border into the forma- 

 tion of which it narrowly enters. The frontal portion retains its 

 breadth forward for nearly half its length when it narrows rapidly to 

 the anterior end. In the longitudinal midline inferiorly the suture 

 between the frontals is obscurely shown in advance of the brain- 

 cavity. 



The parietals contribute about one-third to the margin of the 

 decidedly small supratemporal fossae. 



