164 



MARINE REPTILES OP THE OXFORD CLAY. 



The zygapophyses are very strongly developed and separated from one another in 

 the middle line by a deep fossa; the articular surface of the anterior zygapophysis is 

 slightly convex, the posterior correspondingly concave. The anterior processes project 

 a little beyond the centrum, the posterior rather further, at least in uncrushed specimens. 

 The neural spines slope a little forwards and are much thickened at their upper end, 

 which is roughened and may be longitudinally grooved. It seems possible that some 

 kind of ridge-like dorsal fin was present ; on the anterior border of the neural spine 



Text-fig. 63. 



n.sn. 



First sacral vertebra of Metriorhyneluis moreli: A, from front; B, from behind. (R. 2504, i nat. size.) 



«.;., anterior zygapophysis ; U.S., surface for ilium ; n.sj>., neural spine ; p.z., posterior 



zygapopbysis ; s.r., sacral rib : s.r.f., facet for rib of second sacral. 



is a roughened surface for the attachment of a ligament 



The lumbar vertebras 

 differ only from the dorsals in the absence of rib-facets on the transverse process. 



The two sacrals (text-figs. 63, 64) in general form resemble those of Steneosaurus. 

 In the first (text fig. 63) the anterior articular surface is geutly concave and nearly 



