422 Wortman — Studies of Eocene Mammalia in the 



area by which it is closely applied to the scaphoid and centrale ; 

 externally a similar area for contact with the cuneiform, and 

 distally a deeply saddle-shaped articular surface, divided by a 

 median antero-posterior ridge into two equal parts, for contact 

 with the unciform and magnum. 



The cuneiform is flattened from above downwards and is 

 imperfectly quadrilateral in form, with the postero-external 

 angle much produced, when viewed from above ; its anterior 

 and external surfaces are very rugose, presumably for the 

 attachment of ligaments. Superiorly there is a cup-shaped 

 articular depression for contact with the ulna, while behind 

 this is a postero-external facet by which it touches the pisiform. 

 Inferiorly there is an excavated articular surface by means of 

 which it rests on the unciform. 



The pisiform, like the other bones, has an unusually rugose 

 surface ; it has the usual form and articulation common to the 

 Carnivora, and does not deserve any more extended description. 



The unciform is by far the largest bone of the carpus; it 

 rests almost equally upon the fourth and fifth metacarpals, 

 abutting upon the side against the third metacarpal and the 

 magnum, and supports the lunar and cuneiform. 



The magnum is relatively small, and is remarkable for its 

 great antero-posterior length as well as the low position of the 

 head, — a "form quite unknown elsewhere among the Carnivora. 

 Its articulations are as follows : It rests exclusively upon the 

 third metacarpal ; laterally it develops a contact with the head 

 of the second metacarpal and the trapezoid ; externally it 

 touches the unciform, and superiorly it supports about equally 

 the lunar and centrale. 



The trapezoid is also small in comparison with the other 

 bones of the carpus; it rests upon the second metacarpal, 

 touches the magnum upon its external surface, the centrale 

 and scaphoid above, and upon its internal face exhibits a dis- 

 tinct facet for the trapezium. 



The trapezium is a stout ossicle, somewhat larger than in the 

 dog, which articulates with the scaphoid above and the trape- 

 zoid and second metacarpal externally. It has an irregular 

 triangular shape, and at its distal extremity bears an oval con- 

 vex facet for articulation with the metacarpal of the pollex. 



The last bone of the carpus which remains to be described 

 is the centrale. This is a small antero-posteriorly elongated 

 ossicle which lies at the junction of the scaphoid and lunar, 

 mainly under the former, and resting about equally upon the 

 trapezoid and magnum. When seen from in front, the bone 

 appears to lie almost exclusively upon the magnum ; pos- 

 teriorly, however, it passes over on the trapezoid to a consid- 

 erable extent. 



