. A descriptive catalogue of the marine reptiles of the Oxford clay. Based on the Leeds Collection in the British Museum (Natural History), London ... Reptiles, Fossil. 42 MAEINE EEPTILES OF THE OXFOED CLAY. to the greater transverse convexity of the ventral surface. Above the rib-facet the sides are somewhat flattened and the neural surface is still nearly as broad as in the dorsal region; the rounded and as it were unfinished edges of the centrum show that a good deal of cartilage persisted in this region of the column, even in advanced life. Posteriorly the tail seems to have narrowed very
. A descriptive catalogue of the marine reptiles of the Oxford clay. Based on the Leeds Collection in the British Museum (Natural History), London ... Reptiles, Fossil. 42 MAEINE EEPTILES OF THE OXFOED CLAY. to the greater transverse convexity of the ventral surface. Above the rib-facet the sides are somewhat flattened and the neural surface is still nearly as broad as in the dorsal region; the rounded and as it were unfinished edges of the centrum show that a good deal of cartilage persisted in this region of the column, even in advanced life. Posteriorly the tail seems to have narrowed very rapidly, and the centra become first more rounded, then somewhat compressed laterally, so that they are deeper than wide, and at the same time the rib-facets disappear. This continues till two or three vertebrae of peculiar form (text-figs. 27, C, D, and 28, A, B) are reached. These seem to mark the point where the downward flexure of the column occurs; their centra are much deeper than wide and at the neural border are considerably longer than at the Text-fig. 28. ,„/. Caudal vertebrse of Ojphihalmosaurus : A, centrum of vertebra at bend of tail from front; B, ditto from side ; C, posterior caudal (some distance behind bend) from front; D, ditto from side. (E. 2169, | nat, size.) , facets for chevrons ; , floor of neural canal; , facets for neural arch. ventral. The concavities of the articular faces of the centra are surrounded by a broadly convex border; the middle of the depression bears a deep pit, marking the position of the notochord. The neural canal here forms a narrow deep groove, with the facets for the neural arch raised considerably above its floor. Both in these vertebrse and in a considerable number in front of them, the facets for the chevrons are well marked. Behind the bend of the tail come a large number of vertebrae in which ossification seems to be much more extensive (text-figs. 27, E, F, and 28, C, D) than in the anterior caudals, all the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreptile, bookyear1910
