92 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. XIV. 



contact with the ulna, so close that more than a slight degree of rotation 

 is not probable. 



While the heavy humerus and the broad elbow joint of C&nolestes 

 seem adapted for digging or scratching habits, the character of the fore- 

 arm distinctly tends toward the cursorial type of structure. Aside from 

 a few detailed peculiarities, it may be said that the humerus has con- 

 siderable general resemblance to that of Peramys and Marmosa while 

 the radius and ulna are clearly nearer those of Antechinomys and 

 Sminthopsis or even Perameles. 



BONES OF THE HAND. 

 Plate XVI, Fig. i. 



The carpal bones are eight in number, four in the distal row and four 

 in the proximal row, including the pisiform. In the distal row the 

 trapezium forms the seat of the first metacarpal and is in contact also 

 with the inner proximal extremity of the second metacarpal. Its inner 

 surface articulates with the trapezoid and its inner palmar surface with 

 the distal projection of the scaphoid. It is a short longitudinally com- 

 pressed bone with broad grooves on its distal and proximal surfaces 

 respectively. No sesamoids could be detected in relation with it. The 

 trapezoid and magnum are about equal in size. The former is rounded 

 distally for articulation with the concavity of the proximal end of the 

 second metacarpal. It articulates also with the trapezium, magnum, 

 and scaphoid. The magnum is subtriangular in its anterior or dorsal 

 aspect and articulates with the third metacarpal, the trapezoid, scaphoid 

 and unciform. The unciform is large and roughly pentagonal in outline. 

 It supports the fourth and fifth metacarpals. Its contact with the fifth 

 however is limited to its radial side. The unciform articulates with five 

 bones, viz., the two metacarpals, the magnum, lunar, and cuneiform. 

 Its dorsal surface has two deep pits. The cuneiform receives the head 

 of the ulna in its deeply concave proximal surf a6e. Distally it articulates 

 with the unciform and medially with the lunar. The lunar is quite 

 distinct and presents a triangular dorsal surface about half as extensive 

 as that of the magnum. With the scaphoid it supports the broad head 

 of the radius. The scaphoid is nearly as large as the unciform. It lies 

 between the head of the radius and the trapezoid and sends a curving 

 process beneath the palmar surface of the trapezium. Its medial or 

 ulnar surface is in contact with the lunar. No sesamoids were found 

 associated with it. The pisiform is exceedingly well developed and 

 broadly expanded distally. It is nearly as long as the fifth metacarpal 

 and relatively longer than in any other marsupial which has been 



