96 



MAEINE EEPTILES OF THE OXFOED CLAY. 



vertebrae on which this occurs are sometimes called pectorals (text-fig. 52). The 

 ventral face of the cervical centra is concave from before backwards, and nearly flat or 

 a little convex from side to side ; on the middle line there is a low longitudinal ridge 

 separating a pair of nutritive foramina. The edges of the centrum just before they 



Text-fiff. 52. 



Pectoral and first dorsal vertebrae of Murmiosaurus durobrivensis. (E. 2863, | nat. size.) 

 a.z., anterior zygapophysis ; n.s., neural spine ; p.z., posterior zygapophysis ; r.f., facets for ribs : 



s., neuro-central suture. 



pass into the articular faces are often marked by a series of fine plications, the presence 

 of which seems to have led Phillips * to confer the name Plesiosaurus plicatus on the 

 first named species belonging to the subsequently established genus Murcenosaurus. 



* ' Geology of Oxford ' (1871) p. 313. 



