1914] The Ottawa Naturalist. 19 



narrow, meets the jugal below, and posteriori)- enters largel}' 

 into the formation of the orbital rim. 



By referring to the figure it will be seen that the maxilla, 

 the jugal, the quadrato-jugal, the quadrate, and the mandible 

 have much the same proportions as in Trachodon. The jugal is 

 small, but it has the general shape characteristic of this element 

 in all known members of the Trachodontidae. 



Anteriorly, the premaxilla is somewhat depressed, but 

 laterally much expanded. Its upper surface, next to the median 

 line of the head, is continued in a curve outward anteriorly and 

 backward laterally as a marginal area enclosing a wide depression 

 in advance of the long and narrow nasal opening. In the speci- 

 men, the outermost portion of the laterally expanded premaxilla 

 is crushed down. The nasal opening is enclosed above by the 

 nasal and below by a backwardly directed extension of the pre- 

 maxilla. This extension, or lower limb, of the premaxilla passes 

 along the upper front surface of the maxilla and abuts against 

 the prefrontal. Above, posteriorly, it unites with the nasal 

 behind the nasal opening in a short sutural contact. It is not 

 known how far forward the nasal extends, as its suture with the 

 premaxilla in front has not been detected. 



The squamosal is preserved in part, as shewn in the figure. 

 The postfrontal is probably represented toward its anterior end, 

 but here its limits are not recognized, and posteriorly the bone 

 is imperfect. As in other members of the Trachodontidae, it no 

 doubt contributed to the formation of the postorbital bar. 



The orbital opening is narrowly elliptical, with its longer 

 diameter directed obliquely downward and forward. It is more 

 than twice as long as wide. The lateral temporal fossa is larger 

 than the orbit and is also longer than wide, with a simJlar 

 obliquity of length. 



Detailed descriptions, with illustrations, of the maxilla, the 

 mandible, the teeth, the ischium, the pubis, and the principal 

 bones of the fore- and hind-limbs of Stephanosaurus marginatus 

 were published when the w^riter established the species in 1902. 

 The characters of the integument are known from the writer's 

 recent description (op. cit.). 



The nearest approach to Stephanosaurus is Saurolophus of 

 Brown from a higher horizon of the Cretaceous of Alberta 

 (Edmonton formation). In this latter genus the facial slope of 

 the skull is about midway between that of Stephanosaurus and 

 Trachodon. The upwardly directed nasal spine of Stephano- 

 saurus may have heralded the backwardly sloping nasal crest 



