194 SEXUAL SELECTION : BIRDS. Part IL 



differ from each other chiefly in the points in which 

 they partially resemble their respective males ; and the 

 colours of the males may safely be attributed to sexual 

 selection. With many gallinaceous species the sexes 

 differ to an extreme degree, as with the peacock, phea- 

 sant, and fowl, whilst with other species there has been a 

 partial or even complete transference of character from 

 the male to the female. The females of the several 

 species of Polyplectron exhibit in a dim condition, and 

 chiefly on the tail, the splendid ocelli of their males. 

 The female partiidge differs from the male only in the 

 red mark on her breast beins: smaller ; and the female 

 wild turkey only in her colours being much duller. In 

 the guinea-fowl the two sexes are undistinguishable. 

 There is no improbability in the plain, though pecu- 

 liar s| otted plumage of this latter bird having been 

 accpiired through sexual selection by the males, and 

 then transmitted to both sexes ; for it is not essen- 

 tiallv dilTerent from the much more beautifullv-spotted 

 plumage, characteristic of the males alone of the Tra- 

 gopan pheasants. 



It should be observed that, in some instances, the 

 transference of characters from the male to the female 

 has been effected apparently at a remote period, the 

 male having subsequently undergone great changes, 

 without transferrino- to the female anv of his later- 

 gained eharacteis. For instance, the female and the 

 young of the black-grouse {Tetrao tetrix) resemble 

 pretty closely both sexes and the young of the red- 

 grouse T. Scoticus ; and we may consequently infer 

 that the blaok-o-rouse is descended from some ancient 

 species, of which both sexes were coloured in nearly 

 the same manner as the red-grouse. As both sexes of 

 this latter species are more plainly barred during the 

 breeding-season than at any other time, and as the male 



