384 S. W. WILLI STON 



trochlear surface for the ulna. Both are small, but the joint here 

 was evidently unusually compact and strong. 



The planes of the two extremities of the humerus are turned 

 nearly at right angles with one another. One would not recognize 

 the figure given by Broom of the humerus of Ophiodeirus as that 

 of an allied animal even, much less as that of Araeoscelis, were it 

 not for the statement in the text that the two ends of the specimen, 

 as figured, did not connect with each other. He thought that little 

 was missing and figures the two ends in the same plane, though an 

 examination of the humerus of Araeoscelis, as figured by me, should 

 have convinced him of his error. As a matter of fact, taking as 

 indices the two ends as figured, a slender cylindrical piece of the 

 shaft 12 mm. in length was missing, giving a total length of about 

 50 mm. for the whole humerus, a trifle less than that of the adult 

 humeri here figured. With these corrections his figured humerus 

 may well be that of Araeoscelis. 



There are no complete specimens of radii or ulnae preserved, 

 though there are several partly complete. There can be scarcely 

 a doubt that they were as long as the humerus. In two specimens 

 the proximal ends are preserved in relation with the humerus, and 

 two others have the distal ends preserved in relation with the carpus. 

 Both bones are of equal size and are nearly straight. The radius 

 has a cupped surface at the proximal end and a moderately 

 expanded distal end. The ulna has a moderately produced 

 olecranon; the distal end is a little less broad than that of the 

 radius; there is no articular surface for a pisiform. 



Carpus (Fig. 2, F). — The carpus and hand of Araeoscelis are 

 so unlike those of other known contemporary reptiles that careful 

 study was necessary for their interpretation. Fortunately, how- 

 ever, the material is good, and pretty nearly complete, consisting 

 chiefly of two specimens, both with the carpals nearly all in posi- 

 tion, together with the distal ends of the epipodials and the proximal 

 ends of some of the metacarpals. The better of these specimens 

 has the bones cemented together in a nodule that was inclosed in 

 clay, which was cleanly washed away, leaving the bones visible. 

 The wrist was compressed a little and flexed, so that the radius 

 and ulna had slipped backward and downward, carrying the radiale 



