126 AMERICAN PERMIAN VERTEBRATES 



is not at all visible on the dorsal side of the bone, whereas the 

 trochlear surface is only a little less conspicuous on the dorsal 

 than on the ventral side. The humerus, moreover, is relatively 

 much stouter and longer than in Varanosaurus, whereas the femur 

 is distinctly smaller and shorter. The resemblance of the bone 

 to the humerus of Trispondylus is much closer than to the humerus 

 of Varanosaurus, as will be described later. 



Both forearms of specimen No. 655 were recovered, the right 

 one associated with humerus and hand, the left bones isolated; 

 and in addition a radius and an ulna were found associated with a 

 humerus of No. 656. Some of these bones are slightly bent or 

 otherwise distorted, and the ones figured in Plate XX, Fig. 4, the 

 left bones of No. 655, are not quite as perfect as are the right 

 ones of the same specimen, outlines of which are given in the accom- 

 panying text figure. Both ulna and radius are longer bones than 

 are the radius and ulna of Varanosaurus and are not as much 

 expanded at their extremities. The ulna has the inner border 

 nearly straight, the radial side deeply concave; the radius is 

 nearly straight on the ulnar border, moderately concave on the 

 outer side. The interval between the two bones is much narrower 

 than in Varanosaurus. 



The hand bones of the right side of specimen No. 655 were 

 found close by the distal end of the radius and ulna, but so con- 

 fused that their natural articulations, save in a few cases, could not 

 be determined from their positions. Ten or eleven carpals were 

 more or less attached together, the full number of these; the radiale, 

 ulnare, and pisiform are easily distinguishable by their size and 

 shape. The ulnare resembles that of Varanosaurus (in the restored 

 skeleton, the bone is reversed). The radiale is smaller and more 

 rounded on its proximal surface, permitting apparently greater 

 lateral movement of the hand. The intermedium and second 

 centrale are both rather small, and cannot be differentiated in the 

 single specimen. The fourth and fifth carpalia were attached in 

 natural positions and are determinable with certainty; the fifth 

 is of considerable size, as would be expected from the large size 

 of the fifth finger. The third carpale is also in all probability 

 correctly placed, because of its large size. The chief doubt is 



