608 THE DESCENT OF MAN 



the two sexes are indistinguishable. There is no improba- 

 bility in the plain, though peculiarly spotted plumage of 

 this latter bird having been acquired through sexual selec- 

 tion by the males, and then transmitted to both sexes ; for 

 it is not essentially difEerent from the much more beauti- 

 fully spotted plumage, characteristic of the males alone 

 of the Tragopan pheasants. 



It should be observed that, in some instances, the trans- 

 ference of characters from the male to the female has been 

 effected apparently at a remote period, the male having sub- 

 sequently undergone great changes, without transferring to 

 the female any of his later-gained characters. 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. scoficus); and we may consequently infer that the 

 black grouse is descended from some ancient species, of 

 which both sexes were colored in nearly the same manner 

 as the red grouse. As both sexes of this latter species are 

 more distinctly barred during the breeding season than at 

 any other time, and as the male differs slightly .from the 

 female in his more strongly pronounced red and brown 

 tints," we may conclude that his plumage has been influ- 

 enced by sexual selection, at least to a certain extent. If 

 so, we may further infer that the nearly similar plumage 

 of the female black grouse was similarly produced at some 

 former period. But since this period the male black grouse 

 has acquired his fine black plumage, with his forked and 

 outwardly curled tail feathers; but of these characters there 

 has hardly been any transference to the female, excepting 

 that she shows in her tail a trace of the curved fork. 



We may therefore conclude that the females of distinct 

 though allied species have often had their plumage rendered 

 more or less different by the transference, in various degrees, 

 of characters acquired by the males through sexual selec- 

 tion, both during former and recent times. But it deserves 



>» Macgmivray, "Hist. British Birds," voL i. pp. 1'J2-1U. 



