PLATANISTA. 539 



ning up from the coracoid to the suprascapular border, terminating in a faint notch, 

 one inch posterior to the anterior angle of the suprascapular border, and indicating 

 the position of the mesoscapula and defining a slight fossa in front of it. The pleural 

 surface corresponding to this ridge is the most convex portion of the scapula. There 

 is another slight ridge-like convexity prolonged upwards from on a line with the 

 posterior glenoid border, but not continuous with it. The bone anterior to this is 

 convex from before backwards, so that the interval between these ridges would 

 seem to indicate the existence of a broad mesoscapula. 



Humerus (PI. XLI, fig. 14, h). — The length of this bone nearly equals 

 the united extreme lengths of the antibrachium and carpus. The latter again are 

 equivalent to the metacarpal bone and first phalanx of either of the first, second or 

 third digits. The extreme breadth of the humerus at the radio- ulnar joint is two- 

 thirds of its own length. The narrowest part is immediately below the neck and is 

 more than one-third of its length. The base is antero-posteriorly compressed from 

 the neck to the radio-ulnar joint, where it expands into two nearly equal radial and 

 ulnar surfaces, forming an obtuse angle with one another in the middle Hne, the 

 external being sharp and longer than the internal margin, which is short thick and 

 concave. The globular head is defined by a weU-marked constriction, which, how- 

 ever, does not extend round the external surface, although there is little, if any, 

 motion at the elbow joint. I have never observed the humerus to anchylose with 

 the radius and ulna. 



Radius. — This bone {r) is much flattened and has a convex sharp external 

 border, which is imperfectly ossi&ed in young specimens. Its inner border is short 

 and concave, corresponding to the short but elongately oval interspace that exists 

 between the two bones of the antibrachium. By its distal extremity it articulates 

 with three bones of the carpus, by the two nearly equal surfaces that meet in an 

 obtuse angle. 



TJlna.—T\ns bone («) is flattened, broader than long at its distal extremity and 

 slightly shorter than the radius, and has both of its lateral borders concave, its 

 distal end expanding into two obliquely-placed sm-faces, the proximal of which is 

 much the smaller of the two and concave. 



Bones of carpus (PI. XLI, fig. 14).— These are generally six ia number, 

 but they are subject to great variation even in the same individual, amalgamating 

 with each other and with the ulna, and so being occasionally reduced to three. It 

 does not appear that the fusion is the result of anchylosis dependent on old age, 

 because it has as yet been observed only in comparatively young animals. 



In carpi with six bones, there are three in the proximal row in contact with the 

 radius,— in the distal row one at the extremity of the ulna and common to the fourth 

 and fifth digits ; the remaining two are at the base of the second and third digits. 

 Sometimes the two bones on the pre-axial side of the radius {rd and tm) partially or 

 whoUy unite, the os intermedium (oi) amalgamates with the carpal {mg) at the 

 base of the third digit, and the bone (cu) supporting the fourth and fifth digits 

 coalesces with the ulna. This condition gives only three carpal bones. Hence the 



