No. 5.] SHUFELDT ON THE OSTEOLOGY OF EREMOPIIILA. 141 



The bone liiimerus iu this bird is more remarkable for its lack of curv- 

 ature than anything else, being short and straight, as in others of the 

 suborder among which our subject is classed and belongs. 



The head of the bone is broad and moderately flexed anconad, de- 

 veloping only a very narrow and thin radial crest, which is bent for its 

 entire extent toward the palmar aspect. This crest, answering to the 

 " greater tuberosity " of anthropotomy, and giving attachment to the 

 usual muscles, extends along on a straight line on the upper aspect of the 

 shaft longitudinally for only about half a centimetre. 



The ulnar tubercle, or lesser tuberosity, makes up the thickened and 

 proximal border of the confines of the pneumatic foramen ; a deep little 

 pit on its palmar side or margin lodges the extremity of a strong liga- 

 ment coming from the head of the coracoid of the same side, and mate- 

 rially assists in keeping the head of the humerus in its socket. 



The elliptical and convex articulating facet of the head curls over an- 

 conad, and from its middle a line runs down the bone for a short dis- 

 tance, being one of the angular boundaries of this the trihedral extrem- 

 ity of the bone. Quite a notch exists between the facet just described 

 and the wall of the pneumatic foramen. This latter is on the under side 

 of the head of the bone, surrounded on its upper, proximal, and lower 

 aspects by a firm bony wall, the lower and proximal parts of which are 

 continuous with the smooth and otherwise unbroken surface of the ex- 

 panded and palmar side of the "head". 



The pneumatic fossa thus formed is deep, having at its bottom the 

 foramen alluded to. Quite often the aperture is multiple, and vast 

 differences in size exist, being very large in some individuals, nearly 

 consuming the base of the fossa where it is found. From the lower 

 boundary of the pneumatic enclosure another longitudinal line is seen 

 on the proximal end of the shaft, limiting the anconal face of the trihe- 

 dral end of the humerus in this direction. The palmar aspect of the 

 head, broad and smooth, arches gradually inwards and towards the 

 articular facet; it is also slightly convex from above downwards, 

 supposing the bone to be in situ and in its position of rest, as we do 

 during the course of our description. 



The shaft of the humerus is subcompressed from within outwards, 

 smooth, and, viewing it laterally, it is barely convex above, by virtue of 

 the ends being bent slightly down; viewing it from above, we may say 

 that it is almost straight. 



It retains its form until close under the expanded distal extremity, 

 which is curved palmad. On the radial side of this end of the bone we 

 find the transverse and convex elliptical trochlea below, for the sigmoid 

 articulating depression of the ulna. This has inferiorly the quadrilat- 

 eral internal condyle. 



The ulnar convexity is separated from the oblique tubercle for the ra- 

 dius most effectually by a deep, well-marked, though narrow, notch. 



The oblique tubercle maintains its usual position as formed on this 

 bone in birds generally. 



