CETPTOCLEIDUS OXONIENSIS. 



169 



facets the sides of the centra are flat or slightly concave. The neural arches occupy 

 nearly the whole length of the centra. They bear very strongly developed anterior 

 and posterior zygapophyses, the facets of which are nearly flat in the anterior part of 

 the neck, but further back become somewhat concave and convex respectively from 

 side to side. In the anterior cervical vertebrae the anterior and posterior zygapophyses 

 are connected by a ridge which disappears on the posterior part of the neck. The 



Atlas and axis of Cryptocleidus oxoniensis : A, from right side ; B, from front of a young specimen 



(R. 2417, nat. size) ; C, from rigbt side ; and D, from front of an older specimen (R. 2800, nat. 



size). 

 at.a., arch of atlas; a.iv.h., anterior wedge-bone; ax.a., arch of axis; 7i?/.r., hypapopliysial ridge ; »■.', rib 



of axis ; '/•.'/., facet for rib of atlas ; od., odontoid (centrum of atlas) ; p.z., posterior zygapophysis of 



axis. 



