HATCHER : OLIGOCENE CANIDiE 85 



shallow, cup-like articular surface for contact with the scapho-luDar. This articular 

 surface is continued far down on the styloid process. There is a rather deep groove 

 for the extensor tendon of the pollex and just above this and on the internal side 

 of each radius is a remarkable exostosis. On the anterior and external surface of 

 the distal end of the radius are to be seen the usual grooves for the extensor tendons 

 of the manus. The articular surface for the distal end of the ulna is nearly cir- 

 cular in outline and occupies the same position as in the cats, being decidedly more 

 inferior than that which obtains in the dogs. The shaft of the radius throughout 

 its entire length is subelliptical in cross-section. The shaft of the ulna is much 

 compressed proximally as in the cats, not trihedral as in the dogs. The olecranon 

 process is broad and higher than in the modern dogs, though perhaps not quite so 

 prominent as in the cats. It may therefore be considered as somewhat intermediate 

 in character between the dogs and cats though decidedly more like the latter. The 

 superior and posterior margins of the olecranon are very rugose and much expanded, 

 indicating the presence of a powerful triceps muscle. The greater sigmoid cavity 

 does not differ much from that which obtains in modern dogs. What little varia- 

 tion there is however is seen in the more extended inferior and internal articular 

 surface, due to the greater development of the coronoid process and is in the direc- 

 tion of the cats. Indeed the entire construction of the elbow and limb is remark- 

 ably feline as is seen in the abbreviated forearm, the well-developed coronoid and 

 olecranon processes of the ulna and the presence of a supracondylar foramen in the 

 humerus. Distally the ulna is trihedral in cross-section and there is a moderately 

 developed and flattened styloid process for articulation with the pyramidal and 

 pisiform. On the inner side at the distal end of either radius there is a consider- 

 able growth of diseased bone, or exostosis mentioned above. These are remarkably 

 similar on either side as is shown in Fl. XIX. 



The Carpus. — PL XVIIL, Fig. 10. The carpals of the right manus are all present 

 in our skeleton with the exception of the pyramidal. While that bone is wanting 

 in the right manus it is present in the left, so that it is possible to determine with 

 accuracy the structure of the carpus. The proximal series of carpals consists of the 

 coossified scapho-lunar, the pyramidal and pisiform. In the distal row there are the 

 usual elements, the trapezium, trapezoid, magnum, and unciform. 



The. scapho-lunar is much the largest bone in the carpus. The two elements of 

 which it is made up are so completely united as to leave no trace of a suture. The 

 radial side is a little more depressed than in canis, while the posteiiorly-projecting 

 radiopalmar process is reduced as in the cats instead of expanded vertically as in the 

 dogs. Superiorly there is a regularly convex articular surface for articulation with 



