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Show 74 SEXUAL SELECTION : DIRDS. l'Al~T II. Tho barbs of the feathers in various widely-distinct Lirds are filamentous or plumose, as with some Ilerons, Ibises, Birds of Para.<:hse and Gallinacero. In other cases the barb· disappear, leaving the shafts bare; and these in the ta.il of the Pa'i·adisea apodct attain a length of thirty-four inches.66 Smaller feathers when thus clonuuecl appear like bristles, as on the breast of the tmkey-cock. As any fleeting fashion in dress comes to be admired by man, so with birds a change of almost any kind in tho structure or colouring of the feathers in the male appears to have been aclmir d by the female. ·The fact of the feathers in widely distinct groups, having been modified in an analogous mann r, no doubt depends primarily on all the feathers having nearly the same structure and manner of development, anu consequently tending to vary in the . ·arne manner. 'Ve often sec a tendency to analogous variability in the plumage of our domestic breeds belonging to distinct species. Thus top-knots have appeared in several species. In an extinct variety of tho turkey, the top-knot consisted of bare quills surmounted w.ith plumes of down, so that they resembled, to a certain extent, the racket-shaped feathers above described. In certain breeds of the pigeon and fowl the feathers are plumose, with some tendency in the shafts toLe naked. In the Sebastopol goose the scapular feathers are greatly elongated, curled, or even spirally twisted, with the margins plumose.67 In regard to colour hardly anything need here be said; for every one knows how splendid are the tints 66 Wallace, in' Annuls and Mag. of Nat. llist.' vol. xx. 1857, p. 41G; and in his 'l\Ialay Archipelago,' vol. ii. lSGO, p. 300. 67 'ce my work on 'The Variation of Animals and Plants under Dome~:;tication,' vol. i. p. 280, 233. CIIAP. XHI. DECORATION. 75 ~,f bird.·, and how harmoniously they arc combined. ~he colours are.often metallic and iridescent. Circular ·pots are sometimes surrounded by one or more differently shaded zones, and arc tllU.' converted into ocelli. |