WILLISTON AND CASE: KANSAS MOSASAURS. 1 9 



directed rather more obliquely backward than in the following 

 vertebrae. 



The fourth cervical vertebra differs from the third in having stout- 

 er transverse processes ; in the hypapophysis being directed more 

 nearly downward, and in its smaller size; and in the spine being flat- 

 tened antero-posteriorly toward the base. 



The fifth cervical vertebra differs from the fourth in the broader 

 spine, in the stouter transverse processes, and the smaller hypapophysis. 



In the sixth cervical vertebra, the hypapophysis is reduced to a 

 small ossification, scarcely longer than broad, directed downward. 

 The spine has reached nearly the full width of those of the following 

 vertebrae, though somewhat stouter above. The transverse processes 

 are yet stouter. 



In the seventh, or last, cervical vertebra the hypapophysis is want- 

 ing, or very rudimentary. The under part of the centrum shows a 

 rounded ridge or carina, with a slight projection corresponding to the 

 hypapophysis. 



MEASUREMENTS OF THE CERVICAL VERTEBRAE. 



1. Antero-posterior diameter of intercentrum of atlas. ... 14 millim. 



Transverse diameter of intercentrum 25 



Antero-posterior diameter of lateral piece 20 



Vertical extent of articular surface 17 



Extent of lateral piece 35 



Width of lamina above 16 



2. Length of axis 43 



Transverse diameter of ball 18 



Vertical diameter of ball 17 



Expanse of transverse processes 28 



Elevation of spine above floor of neural canal 34 



Antero-posterior extent of spine 50 



3. Length of third cervical vertebra 37 



Height of spine above floor of neural canal 36 



Depth of hypapophysis below floor of neural canal. • • • 34 



4. Length of fourth cervical vertebra 37 



Height of spine above floor of neural canal 39 



Depth of hypapophysis below floor of neural canal. . • .35 



5. Length of fifth cervical vertebra 37 



Height of spine above floor of neural canal 42 



Depth of hypapophysis below floor of neural canal • • ■ -33 



Transverse diameter of ball 17 



Vertical diameter of ball 18 



6. Length of sixth cervical vertebra 37 



