^52 The Descent of Man. Past II 



for her tail is not nearly so long, relatively to the size of hor 

 body, as that of many female pheasants, nor longer than that 

 of the female turkey. It must also be borne in mind, that in 

 accordance with this view as soon as the tail of the peahen 

 became dangerously long, and its development was consequently 

 checked, she would have continually reacted on her male pro- 

 geny, and thus have prevented the peacock from acquiring his 

 present magnificent traui. We may therefore infer that the 

 length of the tail in the peacock and its shortness in the pea- 

 hen are the result of the requisite variations in the male having 

 been from the first transmitted to the male offspring alone. 



We are led to a nearly similar conclusion with respect to the 

 length of the tail in the various species of phtasants. In the Eared 

 pheasant (Crossoptilon aUritum) the tail is of equal length in both 

 sexes, namely, sixteen or seventeen inches ; in the common phea- 

 sant it is about twenty inches long in the male and twelve in the 

 female ; in Soemmerring's pheasant, thirty-seven inches in the 

 male and only eight in the female; and lastly in Eeeve's phea- 

 sant it is sometimes actually seventy-two inches long in the male 

 and sixteen in the female. Thus in the several species, the tail of 

 the female differs much in length, irrespectively of that of the 

 male ; and this can be accounted for, as it seems to me, with 

 much more probabihty, by the laws of inheritance,— that is by 

 the successive variations having been from the first more or less 

 closely limited in their transmission to the male sex, than by the 

 agency of natural selection, resulting from the length of tail being 

 more or less injurious to the females of these several allied species 



We may now consider Mr. Wallace's arguments in regard to 

 the sexual coloration of birds. He believes that the bright tints 

 originally acquired through sexual selection by the males, would 

 in all, or almost all cases, have been transmitted to the females, 

 unless the transference had been checked through natural selec- 

 tion. I may here remind the reader that various facts opposed 

 to this view have already been given under reptiles, amphibians, 

 fishes, and lepidoptera. Mr. Wallace rests his belief chiefly, 

 but not exclusively, as we shalj see in the next chapter, 

 on the following statement,' that when both sexes are coloured 

 in a very conspicuous manner, the nest is of such a nature 

 as to conceal the sitting bird ; but when there is a marked 

 fiontrast of colour between the sexes, the male being gay and 

 the female dull-coloured, the nest is open and exposes the 

 Bitting bird to view. This coincidence, as far as it goes, cer- 

 tainly seems to ravo'ar the belief that the females which sit or 

 ' Mnmnal of'Trarel,' edited by A. Murray, vol. i. 1868, p. 78. 



