p. 66.) Again, in another genus of night-jars, the tail-feathers are
even still more prodigiously developed. In general the feathers of the
tail are more often elongated than those of the wings, as any great
elongation of the latter impedes flight. We thus see that in
closely-allied birds ornaments of the same kind have been gained by the
males through the development of widely different feathers.
It is a curious fact that the feathers of species belonging to very
distinct groups have been modified in almost exactly the same peculiar
manner. Thus the wing-feathers in one of the above-mentioned night-jars
are bare along the shaft, and terminate in a disc; or are, as they are
sometimes called, spoon or racket-shaped. Feathers of this kind occur
in the tail of a motmot (Eumomota superciliaris), of a king-fisher,
finch, humming-bird, parrot, several Indian drongos (Dicrurus and
Edolius, in one of which the disc stands vertically), and in the tail
of certain birds of paradise. In these latter birds, similar feathers,
beautifully ocellated, ornament the head, as is likewise the case with
some gallinaceous birds. In an Indian bustard (Sypheotides auritus) the
feathers forming the ear-tufts, which are about four inches in length,
also terminate in discs. (69. Jerdon, Birds of India, vol. iii. p.
620.) It is a most singular fact that the motmots, as Mr. Salvin has
clearly shewn (70. Proceedings, Zoological Society, 1873, p. 429.),
give to their tail feathers the racket-shape by biting off the barbs,
and, further, that this continued mutilation has produced a certain
amount of inherited effect.
[Fig. 47. Paradisea Papuana (T.W. Wood).]
Again, the barbs of the feathers in various widely-distinct birds are
filamentous or plumose, as with some herons, ibises, birds of paradise,
and Gallinaceae. In other cases the barbs disappear, leaving the shafts
bare from end to end; and these in the tail of the Paradisea apoda
attain a length of thirty-four inches (71. Wallace, in Annals and
Magazine of Natural History, vol. xx. 1857, p. 416, and in his Malay
Archipelago, vol. ii. 1869, p. 390.): in P. Papuana (Fig. 47) they are
much shorter and thin. Smaller feathers when thus denuded appear like
bristles, as on the breast of the turkey-cock. As any fleeting fashion
in dress comes to be admired by man, so with birds a change of almost
any kind in the structure or colouring of the feathers in the male
appears to have been admired by the female. The fact of the feathers in
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