56 Annals of the Carnegie Museum. 



Limbs: The limbs consist of the greater portion of the shaft of the 

 left humerus with the distal end mutilated, the ulna with the distal 

 end wanting, fragments of the shaft of the radius, and the fifth meta- 

 carpal of the left manus. There are also fragments of the pelvis, the 

 shafts of both femora, right and left tibiae, fragments of the shaft of a 

 fibula, a calcaneum, cuboid, ento- and meso-cuneiforms, all the meta- 

 tarsals except the fifth, a few phalanges of the proximal and median 

 rows, and the proximal portion of one ungual phalanx. 



The limbs of Pleurocyon, as represented in the paratype, No. 3006, 

 are proportionally large, in this respect suggesting Palcearctonyx 

 meadi Matthew. The fragmentary humerus in detailed structure is 

 perhaps more like that of Viilpavus Marsh or Miacis Cope. As in the 

 latter genera, the deltoid and supinator crests are prominent, the 

 entepicondylar foramen is of large size and the entepicondyle was no 

 doubt also of large size. The proximal end of the bone is broken off 

 and the distal end is badly mutilated. It is, however, to be seen that 

 the articular trochlea for the upper portion of the greater sigmoid 

 notch of the ulna is rather deep and narrow. Neither the olecranon or 

 the supratrochlear fossae are deep or high. Whether or not there is a 

 supratrochlear foramen cannot be determined from the specimen. 



The shaft of the ulna is compressed laterally, and is rather straight 

 The lower half of the ulnar, face is broadly and quite deeply channeled. 

 Directly in front it presents a prominent and sharp crest for the 

 attachment of the interosseous membrane, and well down on the 

 radial face there is a second prominent crest, which helps to furnish 

 support for the pronator muscle. The upper portion of the shaft of 

 the ulna is again channeled on its outer face, while radially the shaft 

 is more or less smooth. The coronoid process of the sigmoid cavity 

 is broken off in the specimen, but the broken surface indicates that it 

 was not large. The lesser sigmoid cavity is very shallow, while 

 immediately below, and radial to the coronoid process, there is an 

 unusually deep and large cavity for the attachment of the lateral 

 ligament. The upper portion of the greater sigmoid cavity is com- 

 pressed in order to meet the requirements of the deep and narrow 

 articulation of the humerus described above. The olecranon process 

 is short and truncated. The crescentic groove, over which passes 

 the tendon of the triceps, is narrow, not very deep, and rather obliquely 

 placed, due to the prominent anconeus process and the small develop- 

 ment of the inner anterior margin of the groove. 



