48 THE ROYAL SOCIETY OF CANADA 



mm. 

 Distance between same points measured in a curve over the 



top of the skull 530 



Height, from lower edge of mandible to level of centre of top 



of skull 204 



Length of orbit '. 66 



Height of same 47 



Length of principal cheek-plate in maxillodentary space. . . , 104 



Height of same 59 



Length of mandibular rami 313 



Length of curve of the upper border of the predentary 262 



Width of the predentary posteriorly 142 



Length of external narial opening 71 



Height of same 58 



Breadth of skull behind external nares 155 



Greatest diameter (height) of lateral temporal fossa 59 



Least diameter (width) of same 31 



Height of occipital condyle 41 



Breadth of same 58 



Height of foramen magnum 26 



Width of same " 38 



Mandibular Rami. The two halves of the lower jaw are short and 

 spread widely backward. Posteriorly they have a strong inward curve. 

 In front, they bend in to each other beneath the predentary, which is 

 clearly recognizable in the type as a separate armoured bone. The 

 angle of convergence of the rami is about 68 degrees, using the outer 

 border behind the predentary contact as the line of their general 

 direction. The outer and lower surfaces of the rami, except posteriorly, 

 consist of a thick dermal covering of bone which conceals the mandibular 

 elements, and in the type specimen, the inner surface, except at the 

 back, is hidden by the ossicle and scute-bearing integument filling the 

 space between the rami. The armour does not cover the posterior 

 end of the rami, and here the hinder mandibular elements are seen; 

 not, however, separately in the specimen as the sutures have not 

 been preserved. In separate rami the principal bones would no doubt 

 be recognizable from the inner side. In the type specimen, the cheek- 

 plate of the left side is missing and the wide sweep of the dentary in- 

 ward to the teeth is exposed to view. 



The rami are heavier in the hinder than in the front half of their 

 length. They are deepest at about one-third of their length from the 

 back whence they narrow forward for a short distance, then expand 



