. 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. 74 MAEINE EEPTILES OF THE OXEOED CLAY. in proportion to their width than in the other species ; the chevron-facets on the caudals are large. A number of peculiarly shaped bones (text-fig. 29), preserved with this skeleton, are here regarded as sacral or anterior caudal ribs. At their proximal end they bear a head (/*.) with two facets for union with the lower part of the neural arch and with the centrum ; distally they expand i
. 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. 74 MAEINE EEPTILES OF THE OXEOED CLAY. in proportion to their width than in the other species ; the chevron-facets on the caudals are large. A number of peculiarly shaped bones (text-fig. 29), preserved with this skeleton, are here regarded as sacral or anterior caudal ribs. At their proximal end they bear a head (/*.) with two facets for union with the lower part of the neural arch and with the centrum ; distally they expand into a broad blade, which curves somewhat downwards and is strengthened on the ventral surface by a ridge (r.) running out from the head. They vary in form at their outer ends : in some there is a large terminal facet, perhaps for union with the ilium ; in most the outer end is produced forwards and backwards into a short process terminating in a flat facet (/.), which probably united with the corresponding facet on the rib before and behind. This arrangement would add greatly to the rigidity of the sacral and anterior caudal regions, a condition probably connected with the great development of the hind paddles. Text-fig. Sacral ribs (?) of Pdoneustcs evansi: A, B, from above ; C, from below. (E. 3891, | nat. size.) /., facet for contact with next rib ; 7i., articular head ; ?•., strengthening ridge. Of the pelvis only the ilia are preserved. These expand dorsally into a broad triangular blade much as in Pliosauras, and, as will be seen from text-fig. 25, B, in Peloneustes philarchus also. The upper border is greatly roughened and bears a surface probably for union with the outer end of one or more of the expanded ribs noticed above. The upper part of the outer face of the posterior border has a strongly developed rugosity for muscle-attachment. The fore and hind paddles are much the same as in Peloneustes philarohns, except that the distal expansion of the humerus and fe
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreptile, bookyear1910
