CEEODONTA. 367 



I have also probably restored the length of the shaft (Plate XIX, Fg. 1 ; 

 so as to be too long. 



The radius and ulna are rather stout and are moderately decurved. 

 They present many peculiarities. The inner edge of the ulna is raised so 

 as to be in contact with the radius throughout its length. The external 

 edge of the shaft of the ulna is also elevated nearly its entire length, thus 

 inclosing a wide deep groove with the external edge. This external ridge is 

 the origin of the supinator brevis muscle, and of the extensores pollicis in 

 mammalia, and would appear to indicate unusual power of supination of the 

 hand, and of extension of the thumb. But the form of the head of the 

 radius forbids the idea that that bone could be rotated so as to supinate the 

 hand to much extent. The olecranon is long, and is deep near the coronoid 

 process, and contracts towards its extremity. The coronoid process is 

 elevated and unusually wide, the sides extending upwards so as to be 

 nearly parallel, forming a truncate instead of the usual acuminate summit. 

 The facet band for the radius is slightly concave. The humeral face rises 

 above it on a pi'ocess of the inner side. Immediately anterior to it a nar- 

 row and rather deep fossa extends along the inner superior edge of the ulna, 

 opening onto the general surface of the shaft within a short distance. The 

 interno-inferior face of the shaft of the ulna is convex. The distal extrem- 

 ity is acuminate; its inferior face is flat and is bounded by a ridge with a 

 tuberosity externally. A convexity and then a concavity of the internal 

 surface adapt it to the radius. The carpal extremity projects beyond that 

 of the radius, and is quite narrow in both directions. It has not the double- 

 rib head-like form of that of Oxycena. 



The radius is rather stout. The head is transverse and deeper at the 

 internal than the external side. The humeral surface is double ; one part 

 is concave and occupies the middle of the head ; the other is convex, and 

 is turned outwards to correspond with the internal flange of the humeral 

 condyle. Its prominence is continued from it, presenting inwards, and 

 ceases distally abruptly in a semicircular edge. This strong recurvature 

 of the humeral surface is characteristic of the species. The distal extremity 

 is rather large. Its superior surface presents the wide open groove for the 

 extensor tendons, which is bounded on the outer side by an obtuse ridge- 



