Crocodiles have a much reduced carpus with the radiale and ulnare considerably elongated. The manus in Chamaeleons is curiously modified, having the first three digits arranged in one group and turned inwards, and the fourth and fifth in another group turned outwards; carpalia 3 and 4 are united. In the Pterosauria the anterior limbs form wings, the phalanges of the fifth digit being very greatly elongated to support the wing membrane. The first digit is vestigial and the second, third, and fourth are clawed. THE PELVIC GIRDLE. The pelvic girdle is well developed in all reptiles which have posterior limbs, but is absent or quite vestigial in Ophidia and those Lacertilia which have no posterior limbs. The ilium and ischium agree in their general characters throughout all the various groups of reptiles, but that is not the case with the pubis. In many reptiles such as Chelonia, Ichthyosauria and Lacertilia the ilia are small, more or less cylindrical bones either directed backwards, or vertically placed as in the Chamaeleons. In the Crocodilia they are larger and more expanded, while in Dinosauria and Pterosauria they are greatly elongated both in front of, and behind, the acetabulum. The ischia are generally strongly developed somewhat square bones meeting in a ventral symphysis. In Dinosauria the ischium (fig. 35, 9) is a much elongated and backwardly-directed bone, bearing a forwardly projecting obturator process. In Pterosauria the ischium is fused with the ilium, and in both pterosaurs and crocodiles the ilium and ischium are the only bones taking part in the formation of the acetabulum. In most Lacertilia there is an unpaired structure, the _hypo-ischium_ or _os cloacae_ projecting back from the symphysis ischii, which is usually separated from the symphysis pubis by a large space, the _foramen cordiforme_. In some Lacertilia and Chelonia there is a cartilaginous bar dividing the foramen cordiforme into two obturator foramina; in many Chelonia this bar is ossified. Among _Ophidia_, _Python_, _Tortrix_, _Typhlops_ and their allies have a structure representing a vestigial ischio-pubis: but in most Ophidia there is no trace of the pelvis. In some Theromorpha all the bones of the pelvis are completely fused, forming an os innominatum as in mammals; the pubes and ischia are so completely fused that sometimes as in _Pariasaurus_ even the obturator foramina are closed.