MORPHOLOGICAL REVISION 



lOI 



the shaft, when the head is set with its greatest diameter vertical, as is the 

 case when the foot is advanced, is a strong, ectepicondylar process, standing 

 directly out from the bone. On the upper (posterior) side is a third heavy 

 process at the lower end, fiat above and continuous with the shaft; below 

 this the process is convex from side to side and convex anteroposteriorly; 

 its lower face is continuous with the lower surface of the bone. Opposite 

 this process and entirely on the anterior face of the bone, is the hemispherical 

 surface for the head of the radius. The face for the ulna is confined to the 

 distal end of the bone. The entepicondylar process is of good size, and 

 resembles that of Diadectes in the nearly straight, inner edge. There is, of 

 course, no entepicondylar foramen. 



The ulna has the shaft sharply bent outward; the proximal end is 

 expanded with a shallow, concave face. The olecranon process is short and 

 blunt, and there is no deep concavity to receive the end of the humerus, 

 as on the reptiles. The shaft is triangular in section; the lower end has 

 two facets set at a sharp angle to each other. 



A B C 



Fig. 33. — E. megactphalus. No. 4893 Am. Mus. X yi. 



A. Ulna of right side. 



B. Anterior view of right tibia. 



C. Fibula of left side. 



The radius has the proximal end expanded, with a shallow cup for the 

 hemispherical process of the humerus. The lower end is widely expanded 

 and divided into two faces; one, on the outer side, looks almost directly 

 distally; the other is inclined sharply upward, and looks toward the ulnar 

 side. These faces hardly show on the upper surface, where the distal edge 

 of the bone appears as an unbroken curve. 



The carpus (specimen No. 4186 Am. Mus.) contains eleven bones. 

 They are practically in position, but a little disturbance leaves some room 

 for difference of opinion as to their exact interpretation. There are four 

 bones in the proximal row in contact with the radius and ulna; the two 

 outer in contact with the radius, the third with both radius and ulna, and 

 the inner with the ulna. The element in contact with the radius and ulna 

 together appears as if it might possibly be two bones closely pushed together 

 in fossilization, but it is more likely that it is a single element. There are 



