Chap. XIII. Decoration. 385 



Again the barbs of the feathers iu various widely-distinct 

 birds arey filamentous or plumose, as with some herons, ibises, 

 birds of paradise, and Gallinacese. 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 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 widely distinct groups, having been 

 modified in an analogous manner, no doubt depends primarily 

 on all the feathers having nearly the same structure and manner 

 of development, and consequently tending to vary in the same 

 manner. "We often see 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 the turkey, the top-knot consisted of bare 

 quills surmounted with plumes of down, so that they somewhat 

 resembled the racket-shaped feathers above described. In 

 certain breeds of the pigeon and fowl the feathers are plumose, 

 with some tendency in the shafts to be naked. In the Sebas- 

 topol goose the scapular feathers are greatly elongated, curled, 

 or even spirally twisted, with the margins plumose. 72 



In regard to colour hardly anything need here be said, for 

 every one knows how splendid are the tints of many birds, and 

 how harmoniously they are combined. The colours are often 

 metallic and iridescent. Circular spots are sometimes sur- 

 rounded by one or more differently shaded zones, and are thus 

 converted into ocelli. Nor need much be said on the wonderful 

 difference between the sexes of many birds. The common 

 peacock offers a striking instance. Female birds of paradise 

 are obscurely coloured and destitute of all ornaments, whilst the 

 males are probably the most highly decorated of all birds, and 

 in so many different ways, that they must be seen to be appre- 

 ciated. The elongated and golden-orange plumes which spring 

 from beneath the wings of the Paradisea apoda, when vertically 

 erected and made to vibrate, are described as forming a sort oi 

 halo, in the centre of which the head " looks like a little emerald 

 " sun with its rays formed by the two plumes." 73 In another 



71 Wallace, in ' Annals and Mag. 7I See my work on * The Variation 



of Nat. Hist.' vol. xx. 1857, p. 416 ; of Animals and Plants under Dmueh- 



»nd in his ' Malay Archipelago,' tication,' vol. i. pp. 289, 293. 



rol. ii. 1869, p. 390. :3 Quoted from M. de Lafresnaye, 



