70 SEXUAL SELECTION; BIRDS. [Part IL 



the shafts of the eloiipjated wiiig-feathers are naked, ex- 

 cept at the extremity, where there is a disk." Again, in 

 another genus of niglit-jars, tlie tail-feathers are even 

 still more prodigiously developed; so that we see the 

 same kind of ornament gained by the males of closely- 

 allied hirds, tlirough the development of Avidely-different 

 feathers. 



It is a curious fact that the feathers of birds belonging 

 to distinct groups have been modified in almost exactly 

 the same peculiar mauner. Thus tlie wing-feathers in one 

 of the above-mentioned night-jars are bare along the shaft 

 and terminate in a disk ; or are, as they are sometimes 

 called, spoon or racket-shaped. Feathers of this kind 

 occur in the tail of a motmot [Eumomota snpcrcillaris), 

 of a king-fisher, finch, humming-bird, parrot, several 

 Indian drongos {Dlcrurus and JEklolius, in one of which 

 the disk stands vertically), and in the tail of certain Birds 

 of Paradise. In these latter birds, similar feathers, beau- 

 tifully ocellated, ornament the head, as is likewise the 

 case with some gallinaceous birds. In an Indian bustard 

 {SypJieotides auritus), the feathers forming the ear-tufts, 

 which are about four inches in length, also terminate in 

 disks." The barbs of the feathers in various widely-dis- 

 tinct birds are filamentous or plumose, as with some 

 Herons, Ibises, Birds of Paradise, and Gallinacea?. In 

 other cases the barbs disa])pear, leaving the shafts bare; 

 and these in the tail of the Paradisea apoda attain a 

 length of thirty-four inches.*" Smaller feathers when thus 

 denuded appear like bristles, as on the breast of the 

 turkey-cock. As any fleeting fashion in dress comes to 



" Silater, in the 'Ibis,' vol. vi. 1864, p. 114. Livingstone, 'Expedi- 

 tion to the Zambesi,' 1865, p. 66. 



«* Jeidon, ' Birds of India,' vol. iii. p. 620. 



«« Wiilhico, in 'Annals* and Mag. of Nat. Hist.' vol. xx. 1857, p. 416; 

 and in his ' Malay Archipelago,' vol. ii. 1869, p. 390. 



