32 THE ROYAL SOCIETY OF CANADA 



Supra-occipital. This bone, rising from the exoccipitals, curves 

 backward and becomes horizontal posteriorly between the squamosals, 

 its inferior surface facing directly downward near the posterior margin 

 of the skull. Its junction with the parietal is not traceable, and the 

 amount of its forward extension has not been determined. 



Seemingly Stegoceras shows certain afifiliations with the Stego- 

 sauria but is apparently distinct from both the Stegosauridœ and 

 Ankylosauridœ. The observed differences separating it from both 

 these families make it desirable to refer it to a new family, the Psali- 

 sauridœ which is here proposed for its reception, the name having 

 reference to the form of the vaulted or dome-shaped roof of the cranium. 



The genus Stegosaunis typifying the Stegosauridœ had an un- 

 armoured head, but elsewhere bore plates, spines and ossicles. 



The Ankylosauridge {' Euoplocephalus Lambe and Ankylosaurus 

 Brown) had a head covering of bony scutes, and numerous scutes on 

 the body. 



Stegoceras had no scutes on the head but probably a dorsal 

 armature of scutes was present. 



The head scutes of the Ankylosauridœ, forming a protective 

 covering, became ankylosed to the underlying bones of the skull 

 without conforming to their boundaries. 



In the Psalisauridœ {Stegoceras) protection was provided by a 

 thickening of the investing bones of the upper surface of the skull 

 which met in suturai planes or facets of varying depth. The suturai 

 lines can be traced on the outer surface except where they were effaced 

 through coossification as was usual in the case of the parieto-frontal 

 and interfrontal sutures, and constant between the parietals. The 

 upper surface of the skull is sculptured indicating that scutes were 

 not present. 



In a right squamosal (Cat. No. 2375) obtained in 1917, from the 

 Belly River formation on Red Deer river, the upper surface besides 

 presenting the usual wart-like sculpture develops conspicuous, low, 

 conical projections or spines, pointing upward, in a transverse row 

 above and along the posterior border. This ornamental feature is not 

 present in the type of Stegoceras validus but is highly suggestive of the 

 style of sculpture to be expected, modified or accentuated, in the body 

 scutes of the genus. 



The armoured dinosaurs {Ankylosauridœ) of Belly River and 

 Edmonton age, of which a number in the collections of the Geological 

 Survey await description, have short, more or less triangular heads, 

 flatly convex above. It is probable that among these a number of 

 distinct genera are represented. To the general ankylosaurid shape 

 of head that of Stegoceras to some extent conforms. In the Ankylo- 



