634 PROF. H. G. SEELEY ON [Aug. I9OO, 



straighter. On the anterior surface, the proximal is slightly wider 

 than the distal end. A portion of the shaft is wanting. 



The radius gave attachment to the larger part of the carpus. 



The large size of the radius as compared with the ulna, and the 

 expansion of the ulna at the distal end, are the distinctive features 

 of this segment of the limb, and derive their importance from the 

 resemblances which other parts of the skeleton show of the same type. 

 Both Monotremes have these two bones unlike the fossil in details. 

 The olecranon-process is developed in the following Anomodont- 

 types : — Pareiasaurus, ProcolopJion, Keirognatlms , Theriodesmus, and 

 apparently in Hcrpetocheirus ; while there is no indication of an 

 olecranon-process in Euri/carj)us Oiveni. Tn the latter genus there 

 is evidence of pronation in the crossing of the ulna over the radius, 

 and in that genus also the proximal ends of ulna and radius are 

 articulated, side by side, to the distal end of the humerus. 



(c) The Carpus. 



The carpal bones number 6 or 7. They are separated one from the 

 other, and are mostly of small size ; it is difficult, therefore, without 

 the aid of cartilages, to suppose that the proximal ends of the meta- 

 carpal bones could have articulated with the carpal elements preserved. 

 In the superior aspect there are not more than four bones that can be 

 counted as proximal, two below the radius and two below the ulna. 

 Two are manifestly distal, and between these and the proximal 

 bones is a large ossification. 



(d) The Metacarpus. 



The inferior aspect of the slab shows four metacarpal bones, and 

 the upper surface shows five. The hand is bent backward, and the 

 digits radiate outward. The first is directed forward and the fifth 

 is directed outward. 



The metacarpal bones are longer on the superior aspect thau on 

 the under side, and the bones are individually broader. The 

 proximal ends are flat with a prominent margin. The sides are 

 concave, the concavity being emphasized by the expansion of the 

 extremities. The distal end is thickened and rounded. 



(<?) The Digits of the Hand. 



The phalanges are much shorter than the metacarpal bones. 

 They show the short broad form with expanded ends, and a distal 

 trochlear extremity. In the first digit there appear to be two 

 phalanges, without indication of the claw-phalange. In the second 

 digit are three phalanges and the claw. The third includes three 

 bones. The fourth comprises three phalanges ; but whether the 

 third is the claw-phalange is uncertain. The fifth only shows two 

 phalanges preserved, without any indication of the claw. The 

 claw-phalanges are exposed on their inferior surfaces : they have 

 an inferior callosity below the articulation ; are long, pointed, 

 curved, and compressed, so that they carried sharp claws. 



