14 



E. C. CASE 



(i) PI. II, Fig. 20. The posterior edge of the spine is much 

 thicker than the anterior and is quite flat; the upper end shows 

 a broad surface, smooth and slightly concave, probably for lig- 

 mentous attachment. On the anterior edge there are two small 

 areas very similar to the one on the top of the spine. The 

 anterior edge of the neural spine over- 

 lapped the centrum of the atlas so that 

 the zygapophyses at the point of contact 

 were weak, if developed at all. There is 

 no trace of the sutural connection be- 

 tween the spine and the neural arch, 

 though such a connection did undoubtedly 

 exist in the youth of the animal. There 

 is no pronounced keel on the lower sur- 

 face of the centrum, but the whole body 

 of the vertebrae slants obliquely back- 

 ward, so that the posterior face of the 

 centrum is much lower than the anterior. 

 The transverse process is attached to the 

 base of the neural arch and the upper 

 portion of the centrum ; it curves sharply 

 outward and downward. The distal end 

 5 nat- q£ |.j^g transverse process is lost, but it 

 evidently reached as far down as the 

 lower line of the centrum. The post-zygapophyses are well 

 developed, and the articular faces are horizontal ; the region of 

 the pre-zygapophyses is somewhat injured, but enough remains 

 to show that the processes, if present, were small. The upper 

 half of the centrum only, is occupied by the notochordal canal, 

 so that the notochordal funnel of the anterior face occupies the 

 upper portion of the face, the lower half of the face is occupied 

 by the facet for the intercentrum ; this is shown in profile in the 

 figure. 



MEASUREMENTS OF AXIS. 



Length along bottom line of centrum .... 



Fig. II. — Axis, 

 ural size. 



Distance from top of spine to lower line of the posterior face of 



the centrum 



0.038' 



0.113 



Greatest width of spine - - - 0.054 



Width of the posterior zygapophyses 0,032 



