94 THE ROYAL SOCIETY OF CANADA 



inferior surfaces are flat and broad and there is no inferior median 

 keel. The neurapophyses are weak. They are co-ossified with the 

 external, superior border of the centrum, slightly in advance of the 

 midlength. Most of the right neurapophysis is missing, but the left 

 one is perfect and admirably suited to study and descriptive purposes. 

 Just above its co-ossification with the centrum it is slightly constricted 

 and just above this flares out and sends off two thin processes. The 

 anterior of these runs inward and backward and, with its fellow, 

 formed the incomplete roof of the neural canal. The two were 

 evidently bound together by ligaments and there was no neural spine. 

 The posterior of these processe's (the postzygapophysis) runs back- 

 ward and slightly inward. It is coalesced with the prezygapophysis 

 of the axis though the line of demarcation is faintly shown. 



The parapophysis is on the lower posterior border of the external 

 surface of the centrum and bears a single-headed rib. 



The neural canal is very broad and low, the width being twice 

 the height. 



The axis is firmly co-ossified to the atlas but the line of union is 

 plainly seen. The centrum is short and broad, with the lateral 

 surfaces concave and the superior and inferior surfaces nearly flat. 

 The posterior face of the centrum is cupped. 



The neural arch is low and massive. Interior to the prezygapo- 

 physes the two sides of the neural arch unite, forming a low ridge 

 which runs backward and upward, terminating above in a low, blunt 

 spine. The postzygapophyses are well developed and overhang the 

 posterior border of the axis. The diapophyses are well developed and 

 stand out, at nearly right angles, from the base of the neural arch. 

 They have well-defined, ovate, articular ends which face downward 

 and slightly outward and backward. The parapophyses are not 

 discernible. 



Greatest length of atlas centrum 84 mm. 



Greatest length of axis centrum 54 " 



Greatest height of atlas centrum 48 " 



Greatest breadth of atlas, at anterior edge 72 " 



The third, fourth, fifth and sixth cervicals are very similar in 

 size and proportions to the axis. The height of the centra increases 

 toward the back, but the neural canal retains its broad, low outline. 

 Both extremities of the centra are cupped. The facet for the articula- 

 tion of the head of the rib is well defined on the anterior border of the 

 centrum. It rises on the centra as they proceed backward. The 

 prezygapophyses look up and the postzygapophyses look down. Both 



