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PROCEEDINGS OF THE NATIONAL MUSEUM 



VOL. 77 



The vertebra regarded as the fifth of the cervical series is illus- 

 trated in Figure 8. It differs considerably from those both anterior 

 and posterior to it in having a much shorter centrum, and narrower 

 (antero-posteriorly) neural arch, and in having the anterior articular 

 face at a higher level than the posterior articular, as may be seen 

 in the figure. In an articulated series, this would give the neck a 

 decided upward inflection. This feature is little if at all developed 

 in the other cervicals. The neutral spine also shows the peculiarity 

 of being very thin antero-posteriorly, whereas the spines of the other 

 cervicals both front and back are of the usual stout form. 



The sides of all the cervicals are deeply concave and there is no 

 evidence of a ventral keel. The vertebrae increase in general robust- 

 ness posteriorly ; the di apophyses become slightly longer and heavier, 



Figure 9. — Seventh? cervical vertebra of Palaeoscincus rugosidens. Type. 

 No. 11868, U.S.N.M. A, Lateral view ; B, Anterior view. Both figures 



ONE-THIRD NATURAL SIZE 



the neural canal increases somewhat in size, and the pleuropophyses 

 gradually rise on the side of the centra as is shown in Figure 9A. 

 The spines, however, do not increase in height posteriorly. 



The complete cervical series is as yet unknown in any of the 

 armored dinosaurs from the Upper Cretaceous. Nopsca recognized 

 six as cervical in the articulated skeleton of Scolosaurus in the 

 British Museum, and the atlas and axis and perhaps more were 

 missing from the anterior end of the articulated column. Thus 

 there were at least eight. Gilmore regarded Stegosaumis as having 

 twelve in the complete cervical series. 



