OCR Text |
Show 1886.] TROCHILI, CAPRIMULGI, AND CYPSELID.E. 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 m y article is, that on p. 908, in describing the humerus of Trochilus, the sentence reading " but the radial crest is represented by a strong and gracefully curved hook" should state, instead of the "radial crest," the ulnar tuberosity. Again, in the description of this figure on p. 915, it should say the right humerus instead of the left; and here a3 elsewhere in the paper take into consideration the changes that result therefrom. Now as a correct comparison of these bones is of such high importance, and as I fully intend to carry m y 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 m y knowledge extends, has not its counterpart 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 Trochilus, which, as I have said, is not the case among the Cypselidae, these latter agreeing with the Swallows in this particular in having non-pneumatic humeri. |