. 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. INTRODUCTION. xiii thickened at their upper end. The twenty-eighth vertebra (at the bend) has a high neural spine thickened at its upper end and upright or a little inclined forwards. The spines of the succeeding five vertebrae are inclined forwards and gradually become shorter. On the next the short spine slopes backwards, and the same is the case with the next two. Behind this to the end of the tail—that is, in about the last
. 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. INTRODUCTION. xiii thickened at their upper end. The twenty-eighth vertebra (at the bend) has a high neural spine thickened at its upper end and upright or a little inclined forwards. The spines of the succeeding five vertebrae are inclined forwards and gradually become shorter. On the next the short spine slopes backwards, and the same is the case with the next two. Behind this to the end of the tail—that is, in about the last fifteen vertebrae—no spines can be seen, and probably in some of the terminal vertebra? no neural arch was present. The chevrons begin on the second or third caudal vertebra; at first they are long Y-shaped bones, but from the fourteenth to the twenty-fifth vertebne they are not clearly seen. Behind this they have very short pedicles and a much expanded median ventral portion, consisting of a smaller anterior and a longer posterior lobe. The ends of these lobes in the successive chevrons are in contact, forming a continuous chain Text-fig. mc.+. o a Fore paddle of Geosawus gracilis. (R. 3948, nat. size.) a., radius; 6., ulna; c, radiale ; d., ulnare; , first metacarpal; mcA, fourth metacarpal. as far back as the thirty-seventh vertebra: this arrangement probably greatly strengthened the basal portion of the tail-fin. The structure of the shoulder-girdle and fore limb can, to a great extent, be made out from their impressions on the matrix. The fan-shaped upper end of a coracoid with a coracoid foramen is well shown, and there is a mass of bone crushed beneath the vertebral column, which may be the lower part of a scapula, but the state of preservation is such that this is uncertain. The humerus is wanting, but the form of the paddle-like distal part of the limb is well shown ; this is figured above (text-fig. B). It will be seen that it consists proximally of two p
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectreptile, bookyear1910
