MEUALONYX. 29 



roughened with reticular ridges for muscular attachment. The inner margin is 

 thinner than the outer; and from its lower third it inclines backward, and along 

 the upper part of its course is rough. The radial margui is obtuse, and at the 

 middle it conjoins with a rough ridge ascending posteriorly from the distal end of 

 the bone. Its lower extremity dilates into a domi-ovoid protuberance, which arti- 

 culates with the radius. 



The proximal extremity is not only the broader, but also the thicker part of the 

 bone. Its anterior surface between the coronoid process and olecranon is deeply 

 concave and roughened for muscular attachment. From the corresponding posterior 

 surface there rises a pyramidal process, which supports a cordiform articular facet, 

 about an inch in diameter, for the head of the radius. 



The olecranon is broad and thick, is curved antero-superiorly, and ends in a 

 tuberous apex. Its posterior side is convex and rugged, and at the inner margin 

 of the bone presents a broad, ovoidal surface for the insertion of the extensor 

 cubiti muscle. The coronoid process rises from the radial margin of the bone; and 

 anteriorly it forms a prominent convex tuberosity. At its base postero-inferiorly is 

 a superficial rough process for the tendinous attachment of the brachialis muscle. 



The brachial articular surface (PI. IX, Fig. 7) is two inches in width, and curves 

 in a sigmoid manner from the summit of the coronoid process to the posterior side of 

 the base of the olecranon. In the latter position it is transversely convex, but 

 upon the coronoid process is slightly concave. Longitudinally, from its upper 

 margin to the summit of the coronoid process, it is deeply concave. The radial 

 articular surface is separated from it by a narrow irregular tract. 



The distal extremity of the bone partakes in the general compression, but is 

 thicker and narrower than the middle of the shaft. Its outer margin presents an 

 ovoid tuberosity for articulating with the radius. The inner margin presents a 

 long, trilateral, convex surface, roughened at its lower part for attachment of the 

 internal latei'al ligament of the wrist. 



The carpal articular surface (PI. IX, Fig. 6) rests upon a short cylindroid pro- 

 cess which forms a protuberance anteriorly, corresponding to the technical styloid 

 process. The articular surface inferiorly is an antero-posterior ellipsoidal concavity, 

 prolonged nearly at a right angle upon the antero-internal side of the styloid process. 



Inches. 

 Length of ulna from olecranon to styloid process ....... 20 



Greatest breadth from the summit of the coronoid process ..... 5 



Greatest breadth of distal extremity ......... 3 



Breadth at middle of shaft ........... 3 



The fragments of the ulna in Dr. Owen's collection are rather larger than the 

 corresponding portions of the bone above described. The brachial articulation is 

 confluent with that for the radius, and the two posteriorly form a continuous acute 

 border. Between the radial articular surface and the base of the coronoid process, 

 the bone forms an irregular concave fossa, prolonged below to the radial margin. 

 The corresponding position in the ulna of the Jefferson collection forms a plane 

 above, and becomes convex in its descent. 



The coronoid process is less thick and prominent anteriorly than in the specimen 



