104 



MAEINE EEPTILES OF THE OXFOED CLAY. 



any flexure in the caudal region such as is seen in Ophthalmosaurus. The chevrons 

 (text-fig. 59) are paired compressed rods of bone which do not unite with one 

 another ventrally ; they are usually slightly curved, at least in the anterior part 

 of the tail, where they unite with single facets on or near the hinder border of the 



Caudal vertebra and cbevrons of Mureenosaiirus leedsi : A, posterior caudal from back ; B, same specimen, 

 from right side ; C, middle caudal vertebra from back ; D. same specimen from right side ; E, anterior 

 caudal from back ; F, G, H, three chevron-bones from side. (E. 2864, | nat. size.) 



c, chevron-bones ; c.f., facets for chevron-bones ; c.r., caudal ribs ; /., facets of chevron- 

 bones for articulation Avith caudal centra ; n.s., neural spine. 



centra (c, text-fig. 59, E). Further back they articulate by two facets (c./.) between the 

 centra of successive vertebrae; the two facets make an obtuse angle with each other. 



