SKELETON OF THE CROCODILE. THE MANUS. 265 



The radius and ulna are nearly equal in size and each 

 consists of a long shaft terminated at either end by an epi- 

 physis. 



The radius (fig. 48, A, 2) or pre-axial bone is slightly the 

 smaller of the two. It has a straight cylindrical shaft and is 

 slightly and nearly evenly expanded at either end. The proxi- 

 mal end which articulates with the humerus is flat or slightly 

 concave, the distal end which articulates with the carpus is 

 slightly convex. 



The ulna (fig. 48, A, 3) or postaxial bone is a curved bone 

 rather larger than the radius. Its proximal end is large and 

 convex, but is not drawn out into an olecranon process. 



The Manus consists of the carpus or wrist, and the 

 hand. 



The Carpus. This differs considerably from the more 

 primitive type met with in the Turtle. It consists of six 

 elements arranged in a proximal row of three and a distal row 

 of two, with one intervening. The bones of the proximal row 

 are the radiale, the ulnare, and the pisiform. The radiale 

 (fig. 48, A, 4) is the largest bone of the carpus : it is a some- 

 what hour-glass shaped bone, with its ends formed by flattened 

 epiphyses. It articulates by its proximal end with the whole 

 of the radius, and partly also with the ulna, and by its 

 distal end with the centrale. 



The ulnare (fig. 48, A, 5) is a smaller bone, also some- 

 what hour-glass shaped ; it articulates proximally with the 

 pisiform and radiale, not quite reaching the ulna. The third 

 bone of the proximal row is the pisiform (fig. 48, A, 6), an 

 irregular bone, articulating with the ulna, radiale, and fifth 

 metacarpal. The centrale is a flattened cartilaginous element 

 applied to the distal surface of the radiale. 



The distal row of carpals consists of two small structures. 

 The first of these forms a small cartilaginous patch, which is 

 wedged in between the first and second metacarpals, the 



