No. 5.J SHUFELDT ON THE OSTEOLOGY OF EREMOPIIILA. 143 



From the proximal extremity tlie nearly cylindrical shaft curves 

 <jently palmad from its inner third only ; after that it takes a compara- 

 tively straight course for the wrist. The anconal aspect of the shaft 

 presents at the junction of the inner and middle thirds an elliptical nu- 

 trient foramen, that enters the bone almost perpendicularly to its long 

 axis. The tubercles for the insertion of the bases of the quills of the 

 secondaries, so prominent on this bone in some birds, as in Colaptes, 

 seem to be entirely absent. We find them barely present in Harporhyn- 

 chus, quite strongly marked in Lanius. The carpal extremity of the 

 ulna is likewise articular, being vertically cleft and curved downwards. 

 Anconad it develops a rough eminence, and above a depression for the 

 fan-like expansion of the radius. This end, as in the majority of the 

 class, articulates with the three carpal bones and the radius above. 



The humerus measures 2.4 centimetres, the ulna 3 centimetres, and the 

 radius 2.7 centimetres ; but the bones in situ and the wing closed, the 

 anti-brachium j)rojects beyond the brachium about 5 millimetres. The 

 bones of the forearm, though hollow, are apparently non-pneumatic, as 

 is the case with the carpals and long bones of the manus. 



As in the great majority of the class, the bird-wrist is composed of 

 the two free carpals and the os magnum, which is confluent with the 

 proximal extremity of the second metacarpal. 



The sujierior and smaller carpal is the scaphoid, here an irregularly 

 shajDcd bonelet, introduced among the cubitus, the radius, and the conflu- 

 ent OS magnum, with a distal articular face for the latter and two proximal 

 ones for the trochlete of the anti-brachium. Between the scaphoid and the 

 cuneiform, the other free and inferior carpal, there exists an interspace, 

 where the ulna meets the os magnum. 



The cuneiform has an elongated facet on its outer aspect for the ulna, 

 and two articular processes that grasp the metacarpal below — an arrange- 

 ment that admirably meets the action required of the avian wrist. 



The last carpal merely constitutes the trochlear head of the confluent 

 metacarpals ; by a gentle and backward sweep its general surface is 

 directed inwards. 



The composition of the metacarpal bone of this bird does not deviate 

 from the general rule, as applied to the class, in any important particu- 

 lar. The three long bones comprising it are firmly anchylosed together 

 and bear the fingers. The shortest and first metacari^al, obliquely fused 

 with the anterior and upper end of the second, sui^ports a free and pointed 

 index digit. The second, or "medius", sui)i)orts, first in order below, a 

 phalanx peculiar to birds, that is at once recognized by its expanded 

 posterior border. It is here deeply concave on its inner surface, which 

 concavity is i)artially divided by a feeble transverse line. 



The " blade " of this bone is quite thin in some birds, though the gen- 

 eral surface is absorbed, leaving nothing but the rounded and limital 

 borders, as in Lams delaicarcnsis and others. 



The neck of this bone is but moderately constricted between the blade 



