110 The Ottawa Naturalist. [Dec. 



large posterior processes of the frill on the left side had lost 

 about three and six inches respectively from off their pointed 

 ends. These parts were not found. On the right side, the 

 jugal had fallen to pieces and the lateral border of the frill had 

 suffered some damage from exposure. The posterior processes 

 had been broken off and fractured, but, with the exception of 

 a few r fragments, they were recovered and have been restored 

 and replaced in position. 



The front part of the skull has been crushed down to some 

 extent. This has caused an overlapping of some of the bones, 

 notably at the junction of the nasals with the premaxillae and 

 maxillae, and along an irregular line through the lachrymal 

 foramen, the lower rim of the orbit and the lower edge of the 

 postfrontal. The orbits and the lateral temporal fossae have 

 been reduced in vertical diameter and the left jugal has been 

 squeezed slightly outward below*. 



This specimen brings to light an entirely new phase of 

 frill development, which is unique among the horned dinosaurs. 

 It may be regarded as one of the most complete and best pre- 

 served of the Ceratopsian skulls hitherto discovered in Cre- 

 taceous deposits of this continent. 



The name selected for this genus has reference to the shape 

 of the large processes on the frill, which resemble spikes, and must 

 have made this bristling reptile in life a, veritable moving 

 chevaux de frise. 



Viewed from above, the skull presents a facial wedge-shaped 

 portion from the orbits forward, a middle section which broadens 

 abruptlv into a somew r hat circular expansion and includes the 

 anterior half of the neck-frill, and a hindermost part formed 

 of the widely divergent posterior processes which add so greatly 

 to the length and breadth of the frill. 



In lateral aspect the skull is depressed and very long in 

 contrast with its height. The spike-shaped processes double 

 the length of the frill, which, without them, would compare 

 favourablv in relative size with the corresponding expansion in 

 later forms of the Ceratopsia, such as Triceratops, in which the 

 orl it is hut slightlv in advance of the mid-length of the skull. 

 Behind the nasal horn the upper outline is straight, then some- 

 what depressed near the middle of the crest, finally rising 

 to its highest point at the termination of the hindermost process. 

 The orbital rim rises above and breaks the continuity of the 

 superior outline of the head. Midway between the posterior 

 rim of the orbit and the anterior end of the nasal the straight 

 nasal horn rises abruptly, with a slight inclination forward, and 

 is the most conspicuous feature of the anterior part of the head. 



