[lambe] cretaceous GENUS STEGOCERAS 35 



saurus, Scelidosaurus, etc.) and the AnkylosauridcB Ç Euoplocephalus 

 and Ankylo saurus) . The new family, the Psalisauridœ, proposed for 

 its reception, is provisionally referred to the Stegosauria, ranking 

 equally with the above subdivisions of the armoured dinosaurs. 

 Possibly it may be found necessary when more is known of the struc- 

 ture of Stegoceras to advance the family to higher rank among the 

 divisions of the Orthopoda (Predentata) under the name Psalisauria. 



. For the present the characters of this extraordinary reptile may 

 be summarized as follows: — 



Psalisauridœ, fam. nov. 



Family characters. — Skull small, with outer investing bones 

 greatly thickened and meeting in deep suturai facets. Bone struc- 

 ture dense, prismatic. No dermal head plates. 



Generic characters. Skull triangular, ending broadly and squarely 

 behind. Occiput overhanging. Parietals and frontals coossified, 

 and thickened to form a broadly convex elevation in the upper surface 

 of the skull. Orbital cavities large, extending far inward. Latero- 

 temporal fossae large. Supratemporal fossae reduced. Brain small, 

 broad in comparison with its length. 



Stegoceras valid us. Generic and specific type. Cat. No. 515. 

 Belly River formation. Red Deer river, Alberta, east side, below the 

 mouth of Berry creek, Aug. 15, 1898. Described and figured in 1902 

 (op. cit. ante, p. 68, pi. XXI, figs. 1 and 2). 



Stegoceras brevis, sp. nov. Specific type. Cat. No. 1423, Belly 

 River formation. Red Deer river, east side, below Berry creek, Aug. 

 24, 1901*; referred to in 1902 (op. cit. ante, p. 68, pi. XXI, figs. 3, 4 and 

 5) under the name 5'. validus as the smaller of two specimens figured. 

 The opinion was then expressed that the smaller specimen might 

 belong to a species distinct from S. validus. 



That two species of Stegoceras are represented by the specimens 

 from Red Deer river is now made clear by the additional structural 

 information supplied by specimen No. 138. 



The second species, for which the name brevis is proposed, differs 

 in the following particulars from 5. validus: — 



The parieto-frontal mass is shorter in comparison with its breadth. 



The upper parietal surface between the squamosals instead of 

 extending backward almost horizontally or at a moderately 

 inclined downward slope to the posterior border curves con- 

 vexly downward so as to become almost vertical posteriorly. 



