1886. | TROCHILI, CAPRIMULGI, AND CYPSELIDE. 503 
Be this as it may, the oversight has been kindly pointed out to me 
by Mr. F. A. Lucas, the osteologist of the United States National 
Museum, and it devolves upon me to set the matter right. 
The only changes it demands in the text of my article is, that on 
p- 908, in describing the humerus of T’rochilus, the sentence reading 
“but the radial crest is represented by a strong and gracefully 
curved hook”’ should state, instead of the “radial crest,” the udaar 
tuberosity. Again, in the description of this figure on p. 915, it 
should say the vight humerus instead of the left; and here as else- 
where in the paper take into consideration the changes that result 
therefrom. 
Nowas a correct comparison of these bones is of such high import- 
ance, and as I fully intend to carry my comparisons of the structure 
of these groups still further, I have redrawn, increasing in size and 
presenting two views, the humeri of the forms under discussion, and 
offer these drawings here as illustrations to the present article. 
From an examination of figures 1 and 2, it must be evident, to any 
one familiar with the ordinary form of the avian humerus, that in 
the Swallow the bone departs to some extent from the more common 
Shape it wears among the Passeres. The principal departure, 
however, consists in a marked shortening of the shaft, and perhaps 
a comparatively more conspicuous radial crest. The bone is likewise 
non-pneumatic. This also we find to be the case in the Swift, where, 
too, the radial crest is drawn out into an upturned hook, and the 
ulnar tuberosity is simply drawn out further and consequently more 
hook-like. 
Now turning to the Humming-bird (figs. 5 and 6), we find a 
humerus that, so far as my knowledge extends, has not its counter- 
part among living birds. In the first place, the extraordinary position 
of its pneumatic fossa, being on the radial side of the bone, is an 
exception to every general definition of a bird’s humerus that the 
writer has ever met with. Of the peculiar method of insertion of 
the pectoralis major muscle in this bird I shall have something to 
say in a future contribution. As will be seen from the figures, 
the ulnar tuberosity is a prominent decurved process, and one of the 
most striking features of this curiously twisted bone. It would be 
superfluous on my part to point out in the figures the manifest 
differences existing between the humerus of this Hummer and the 
Swift; they are even greater than I thought them to be, before I 
made the oversight above quoted. In addition to its general form, 
the humerus is highly pneumatic in Zrochilus, which, as I have said, 
is not the case among the Cypselide, these latter agreeing with the 
Swallows in this particular in having non-pneumatie humeri. 
