158 "" SEXUAL SELECTION: BIRDS. [Part II. 



possesses ; for her tail is not nearly so long, relatively to 

 the size of her 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 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 pheas- 

 ants. In the Eared pheasant ( Crossoptilon auritum) the 

 tail is of equal length in both sexes, namely, sixteen or 

 seventeen inches; in the common pheasant it is about 

 twenty inches long in the male, and twelve in the female ; 

 in Scemmerring's pheasant, thirty-seven inches in the male, 

 and only eight in the female ; and lastly in Reeve's pheas- 

 ant it is sometimes actually seventy-two inches long in the 

 male and sixteen in the female. Thus in the several spe- 

 cies, the tail of the female differs much in length, irrespec- 

 tively 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, owing to the length of tail having 

 been injurious in a greater or less degree to the females of 

 the several species. 



We may now consider Mr. Wallace's arguments in re- 

 gard to the sexual coloration of birds. He believes that 



