718 



H. G. SEELKY ON THE VERTEBRAL COLUMN 



The axis is not so well preserved as the atlas, being a little 

 weathered on the neural surface and a little crushed on the posterior 

 part of the basal surface ; it is a transverse ellipse, 2]^ inches wide 

 posteriorly and 2 T 7 g- inches deep. The articular surface is concave, 

 and terminates laterally in a slightly bevelled border. 



The lower part of the side of the centrum has an articulation for a 

 rib (e, fig. 2). The facet is on a level with the base of the centrum, 

 and looks outward and somewhat downward. Its pedicle is slightly 

 elevated, subquadrate, and separated from a very small superior 

 facet by a narrow groove ; it does not reach within £ inch of the 

 posterior border of the centrum. 



Other Cervical Vertebra? (figs, 3, 4). 



As the cervical vertebra? succeed each other backward they increase 

 slightly in size and length, but do not appear otherwise to materially 

 change their characters, except in the gradual elevation of the arti- 

 cular facet for the cervical rib. 



The third cervical has the centrum 2-f inches deep and 3 inches 

 wide in front. The margin of its articular face is conspicuously 

 bevelled. The base of the centrum is marked with a median ridge, 

 between which and the pedicles for the ribs are depressed areas, each 

 showing in the centre a vascular perforation. 



Fig. 3. — Right Side of Fourth 

 Cervical Vertebra, showing 

 the divided articulation for 

 the ril 



Fig. 4. — Posterior Articular Surface 

 of Centrum of Fourth Cervical 

 Vertebra ; 



g nat. size. 



1| nat. size. 



The pedicles for the ribs are 1| inch deep, 1^ inch wide' where 

 widest, and divided into two subequal parts by a transverse 

 groove ; each of these articular areas is deeply concave. The 

 antero-posterior measurement of the centrum on the neural canal is 

 1| inch ; but it is rather longer at the baee. The articular face of 

 the centrum is somewhat concave, and has in its centre a puncture- 

 like depression. 



The sixth and seventh are adherent vertebrae, with portions of 

 displaced neural arch and cervical ribs preserved. They have the 



