80 ODOXTOKNTTHES. 



Tlie anterior articular face of the centrum is convex, broadly ovate 

 in outline, and slightly notched above, below the neural canal. The 

 posterior articular face is similar in form, and slightly concave. 



The transverse processes are stouter than in the last vertebra, and their 

 distal ends are thickened, and abruptly truncated. The axes of these 

 processes, if continued to the axis of the neural spine, would meet in the 

 neural canal, and form equal angles with it and with each other. The 

 neural spine is elevated and massive, and its posterior margin is nearly 

 vertical. Its apex is bent forward and expanded, and is cordiform in 

 superior outline. The neinal arch covers the whole of the centrum, and 

 the canal is large, and vertically ovate in outline. 



Measurements of TJiircl Caudal Vertebra. (No. 1200.) 



Length of centrum, '. 12.0 mra 



Least diameter, below transverse processes, ■_ 9.0 



Transverse diameter of anterior articulation, . 13.0 



Vertical diameters of anterior articulation, 10.0-11.0 



Transverse diameter of posterior articulation, 12.5 



Vertical diameters of posterior articulation, L. 10.0-11.6 



Diameter of vertebra, across transverse processes, 32.0 



Length of floor of neural canal, 10.0 



Length of roof of neural canal, '. . 8.5 



Vertical diameter of anterior opening of neural canal, __ 5.0 



Vertical diameter of posterior opening of neural canal, 5.0 



Transverse diameter of posterior opening of neural canal, 4.0 



Height of neural spine, above floor of neural canal, 22.0 



Transverse diameter of shaft of neural spine, 3.0 



Transverse diameter of head of neural spine, 6.0 



Antero-posterior diameter of diapophysis, at base, 6.5 



The Fourth Caudal Vertebra. (Plate XII, figure 4.) 

 The fourth caudal vertebra is similar in many respects to the one last 

 described, but the centrum is materially longer. The anterior articular 

 face is considerably smaller than in the third vertebra. It is somewhat 

 concave, and so deeply notched above for the neural canal as to be sub- 

 cordate in outline. The posterior face is similar to that of the last 

 vertebra, but the transverse processes are stouter, and extend more directly 

 backward. The neural arch, when seen from the front, is very similar to 

 that in the preceding- vertebra, but its spine is shorter, and its cordiform 

 apex is broader, and more' turned forward. 



