380 THE DESCENT OP MAN. 



fact that the motmots, as Mr. Salvia has clearly shown,™ 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. 



Again the barbs of the feathers in various widely-distinct 

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

 birds of paradise, and Gallinaeeas. 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;" in P. Papuana (flg. 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 coloring 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 witn 

 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 Sebastopol goose the scapular feathers 

 are greatly elongated, curled, or even spirally twisted, with the 

 margins plumose.'- 



In regard to color 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 colors are often 

 metallic and iridescent. Circular spots are sometimes surrounded 

 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 col- 

 ored and destitute of all ornaments, whilst the males are prob- 

 ably the most highly decorated of all birds, and in so many dif- 

 ferent ways, that they must be seen to be appreciated. The elon- 

 gated and golden-orange plumes which spring from beneath the 



™ 'Proc. Zoolog. Soc' 1873, p. 429. 



'1 Wallaoe, in 'Annals and Mag. of Nat. Hist.' vol. xx. 1857, p. 416; 

 and in his 'Malay Archipelag-o, vol. ii. 1869, p. 390. 



'= See my work on 'The Variation of Animals and Plants under 

 Domestication,' vol. 1. pp. 289, 293. 



