PHENACODDS. 477 



when it rises and for the remainder of the length is slightly concave. Be- 

 tween the humeral cotylus and this rise the shaft is triangular in section. 

 Distad to this point is a compressed oval, since the external ridge descends 

 to become part of the inferior border, forming an obtuse rib across the ex- 

 ternal side of the shaft. The olecranon is rather long and compressed, with 

 superior acute edge and concave internal side. It is about as deep as the 

 deepest part of the shaft, and is thickened below and distally. The humeral 

 cotylus is flared behind on the external side only, and below most on the 

 internal side. Below the internal flare to the middle of the length the side 

 of the shaft is gently concave. The distal extremity has a flattened tri- 

 angular section, and terminates in a small rounded tuberosity. 



The radius is not much expanded at the head, and a horizontal section 

 of its humeral surface is sigmoid, to suit the humerus. The external angle 

 is obtuse and short, and turned slightly posteriorly. The shaft at its mid- 

 dle is a little flattened horizontally; more distally it is cylindric. The dis- 

 tal extremity is stout and not depressed. The superior tendinous groove is 

 wide and shallow, while the supero-external groove is bettor defined by a 

 short prominent longitudinal ridge below it. The articular surface is not so 

 much contracted as in the P. primcevtis, and the facets are relatively wider 

 anteroposteriorly. The scaphoid and lunar facets are faintly distinguished 

 from each other, and in each the anteroposterior exceeds the transverse diam- 

 eter. A small flat internal tuberosity and a similar posterior (inferior) one. 

 Extei'nal tubei'osity larger and more prominent. 



Measurements of fore limb. 



M. 

 Length of humerus 113 



( anteroposterior (greatest) . 032 



Diameter of proximal end 2 c at bicipital groove 0155 



^ < at lesser tuberosity 021 



Anteroposterior diameter of shaft at middle 013 



Width at epicondyles 028 



Width of condyles distally ' 019 



Anteroposterior diameter of condyle^ ^^ ^^^^i J ■■ 01^ 



( internally 015 



Length of ulna 131 



t extremity of olecranon 012 



Depth of ulna at < corouoid process 019 



( middle of shaft 010 



Diameters of distal tuberosity^ "^^ertioal 005 



t transverse. 004 



