OPHTHALMOSAURUS. 



41 



become steeper towards the centre, there cannot be said to be any flattened area 

 round the periphery. 



In the anterior caudal region (text-figs. 26, A, C, and 27, A, B) the form of the 

 centra is very similar to that of the posterior dorsals, but, in addition to the general 

 concavity of the anterior and posterior faces, there is often a deep pit in the middle of 



Test-fig. 27. 



Caudal vertebras of Ojphthalmosaurus : A, anterior caudal from front ; B, ditto from side ; C, middle caudal 

 vertebra (at bend of tail) from front ; D, ditto from side ; E, vertebra from just bebiud bend of tail, 

 from front ; F, ditto from side. (E. 3534, | nat. size.) 



C, facets for chevrons ; n.a., neural arch ; n.c, neural canal ; )•., rib. 



the centrum, which is thus nearly perforated. In this region the ribs are small 

 irregular nodules of bone (r., text-fig. 27, A, B), and seem to have been of this form 

 till they disappear altogether. In the middle caudals the single oblique rib-facet 

 extends the whole width of the centrum, and appears to be higher up the side owing 



G 



