Page:The Osteology of the Reptiles.pdf/190

172 present. In Procolophon only, of the Cotylosauria, is this centrale absent, as is also affirmed of the radiale. Throughout the Theromorpha, as known in numerous forms, the carpus is primitively complete, save that the first centrale and fifth carpale remained cartilaginous in one known genus, Varanops.



. 138. Limbs: A, Theriodesmus (Therocephalia), front leg, dorsal side (rearranged from Seeley). One half natural size. B, Scymnognathus (Therocephalia), front foot. After Broom. One third natural size. C, Protorosaurus (Protorosauria), front leg. After von Meyer. One half natural size. D, hind leg of same. E, F, Araeoscelis (Protorosauria), part of tarsus, F probably immature. Nine eighths natural size. G, Sceloporus (Lacertilia). Enlarged.

Among the reptiles collectively known as the Therapsida, the carpus is ill known. In Galechirus of the Dromasauria (Fig. 137 ) as figured by Broom, the primitive structure is retained, as it also is in Dicynodon and its allies of the Anomodontia. The carpus of Scymnognathus of the Theriodontia, as figured by the same writer (Fig. 138 ) has a small intermedium, and the fifth carpale is represented as fused with the fourth, an error. A small element found near the first carpale was referred to a possible prepollex, or a radial sesamoid. Among