446 THE DESCENT OF MAN. 



came dangerously long, and its development was consequently 

 checked, she would have continually reacted on her male progeny, 

 and thus have prevented the peacock from acquiring his present 

 magnificent train. We may therefore infer that the length of 

 the tail in the peacock and its shortness in the peahen 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 pheasants. In the 

 Bared pheasant (Crossoptilon auritum) the tail is of equal length 

 in hotli sexes, namely, sixteen or seventeen inches; in the com- 

 m.on pheasant 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 

 Reeve's pheasant 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, irrespective- 

 ly of that of the male; and this can be accounted for, as it seems 

 to me, with much more probability, 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 shall see in the next chapter, on the fol- 

 lowing statement,' that when both sexes are colored in a very 

 conspicuous manner, the nest is of such a nature as to conceal 

 the sitting bird; but when there is a marked contrast of color 

 between the sexes, the male being gay and the female dull-col- 

 ored, the nest is open and exposes the sitting bird to view. This 

 coincidence, as far as it goes, certainly seems to favor the belief 

 that the females which sit on open nests have been specially modi- 

 fied for the sake of protection; but we shall presently see that 

 there is another and more probable explanation, namely, that 

 conspicuous females have acquired the instinct of building domed 

 nests oftener than dull-colored birds. Mr. Wallace admits that 



" 'Journal of Travel,' edited by A. Murray, vol. i. 1S6S, p. 78. 



