OCR Text |
Show 1886.] CUBITAL COVERTS OF BIRDS. 187 species of Passerine birds, and will probably, on further examination, be found to characterize the whole of the birds that are correctlv referred to that Order. In the Corvidae an approach towards a somewhat different mode of arrangement is made (fig. 3) : another minor modification is seen in the Alaudidse (fig. 3a). The Swallows (fig. 5a, p. 188) all appear to follow the normal passerine type. That of the Swifts and the Cotingas appears to m e to be essentially different. There is some doubt also in regard to the Bower-birds and the Birds of Paradise in this respect. Following Dr. Sclater's arrangement, the Swifts and the Humming- Turdus merula. Corvus. Alauda arvensis. birds fall next to be described. Living Humming-birds can very rarely be examined closely ; I have therefore been compelled to rely entirely upon the examination of museum specimens. After examining the whole of the Gould Collection, and checking the results by comparing them with those made on a large series of other specimens, I am convinced that one general type of wing-pattern characterizes the whole of these birds; it is of a very simple character, and is represented in figure 4, p. 188. By this it will be seen that the proximal lapping row of median coverts found throughout all the Passeres is absent entirely in this. The Humming-birds might, indeed, be described as possessing no median coverts at all, the place of these being taken up by feathers having the same mode of imbrication as the Lesser Coverts. All the feathers of each series overlap outwards and backwards from the vertebral axis towards the distal end of the wing in these birds. Observations on the order of overlap in the wing of freshly-killed specimens of Cypselus apus, afterwards extended by an examination of the whole series of Swifts in the National Collection, showed that in these, as in the Humming-birds, no one series of feathers overlaps backwards. In fact the wing-pattern in the genera Cypselus, Acanthylis, Chcetura, and Collocalia seems to me to differ in no essential respect from that found throughout the Trochilidse. So far as the disposition of the wing-coverts is concerned, the Swifts and Humming-birds agree amongst themselves, and differ from all of the Passeriform birds, with the possible exception of the Birds of Paradise. Fig. 5, p. 188, taken from a freshly-killed specimen of Cypselus apus, will serve to make this point clear. A wing of Hirundo rustica is fio-ured alongside for comparison (fig. 5 a). |