24.2 
Sternum. 
The three portions of the sternum of Cnemiornis include the right costal border and 
process (PI. LXVI. figs. 5 & 6), part of the left (figs. 7 & 8), and the middle part of the 
bone (fig. 9)'. ‘The costal border (c) is 3 inches 6 lines in length, and includes seven 
articular ridges (h) for the sternal ribs, the last contracting to the form of a tubercle ; 
and there is also a tubercle of smaller size at the angular beginning of the border. The 
costal process (d) is quadrate, slightly concave on the inner side, convex lengthwise 
on the outer side, and smooth, as if for some articulation ; the pneumatic foramina are 
at the base of this process, on the inner side of the sternum, and are also seen at the 
costal border, at the interspaces of the articular ridges. The posterior boundary of 
what appears to be the short, shallow and narrow coracoid groove (6) extends from 
above these foramina towards the middle line, but apparently not far: the body of the 
sternum has been broken away from near the base of the costal process. The greatest 
breadth of the body of the sternum preserved, at the end of the costal border (fig. 5, ¢, a), 
is | inch 8 lines; the length of this right portion of the sternum preserved is 4 inches 
5 lines, and shows no trace of posterior notch; it is gently convex lengthwise, concave 
transversely, but in a less degree; and the fore part of the sternum, for more than an 
inch behind the costal process, shows a shallow excavation. A smaller proportion of the 
body of the sternum remains connected with the left costal margin: it cannot, there- 
fore, be positively affirmed that the keel was absent, but this may be inferred from the 
thinness of the sternum at the fractured mesial margins (a’) of the two lateral portions. 
From the sternum of Notornis that of Cnemiornis differs in the greater extent and dif- 
ferent direction of the costal border, the greater number of articular ridges thereon, the 
presence of the costal process, and the much greater breadth of the body of the 
sternum. 
The middle portion of the body of the sternum (fig. 9) includes a length of 42 inches, 
with a breadth of 27 inches, of that part of the bone. Its thickness does not exceed 
2 lines at the fore and mid part. It is very feebly convex externally, and correspond- 
ingly concave on the opposite surface. A pair of shallow muscular surfaces nearly 
meet at a slightly raised median tract (s), convex transversely, and from 2 lines to 3 lines 
across, extending from the anterior fractured margin about 1 inch along the bone, leaving 
more than 3 inches beyond free from even this feeble indication of a keel. 
Humerus. 
The humerus (Pl. LXIX. figs. 7-10), by its small size, slender proportions, and feeble 
development of the parts at the proximal end, accords with the characters of the 
sternum, and indicates the incapacity of the Onemiornis for flight : the articular head (a) 
1s Narrow in proportion to its length, and is not broader or more convex at its 
middle part, as in birds of flight; its margin projects posteriorly, but anteriorly falls 
* These figures have been drawn on the stone, without being reversed, 


