. 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. PELONEUSTES. 53 neural spines seem to have been broader and lower than in the cervicals. The transverse processes are stout and slightly curved, the concavity being downwards; they enlarge a little at their outer end, which terminates in a nearly flat surface for union with the rib. In the posterior part of the back the centra seem to decrease in height, and in the sacrals they are considerably wider than high. The caudal centr
. 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. PELONEUSTES. 53 neural spines seem to have been broader and lower than in the cervicals. The transverse processes are stout and slightly curved, the concavity being downwards; they enlarge a little at their outer end, which terminates in a nearly flat surface for union with the rib. In the posterior part of the back the centra seem to decrease in height, and in the sacrals they are considerably wider than high. The caudal centra are likewise wider than high, and at the same time are shorter than the dorsals. The caudal ribs articulate with deeply concave surfaces, the rims of which form well- marked projections on the sides of the centrum. Beneath the rib-facets the sides of the centrum are gently concave in all directions; they pass into the nearly flat ventral surface in rounded ventro-lateral angles, which are truncated both anteriorly and posteriorly by oblique chevron-facets. The last few caudal centra decrease in size very rapidly; in the last preserved, the neural arch was present and the chevron-facets Text-fig. Cervical ribs of Peloneustes philarchus : A, B, anterior ; C, middle ; D, posterior ribs. (R. 3318, § nat. size.) , lower (parapophysial) facet; , upper (diapophysial) facet. were relatively much larger than in the more anterior caudals ; this may indicate that there was a small vertical fin-like expansion at the end of the tail. Unfortunately, no chevrons are preserved. In the cervical region, as noted above, all the ribs (text-fig. 20), with the exception of one or two at the hinder end of the series, are double-headed ; the upper () and lower () facets are separated by a notch or groove ; towards their distal end, at least in the anterior part of neck, they are strongly compressed from above downwards, and widen out so that their outer end is produced a littl
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreptile, bookyear1910
