514 THE DESCENT OF MAN. 



hole; and, as I am informed by Mr. K. B. Sharpe, these 

 feathers become much crumpled during incubation. 



In these two latter cases the great length of the tail- 

 feathers must be in some degree inconvenient to the female; 

 and as in both species the tail-feathers of the female are 

 somewhat shorter than those of the male, it might be 

 argued that their full development had been prevented 

 through natural selection. But if the development of the 

 tail of the peahen had been checked only when it became 

 incor veniently or dangerously great she would have retained 

 a much longer tail than she actually 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 conse- 

 quently checked, she would have continually reacted on her 

 male prdgeny, and thus have prevented the peacock from 

 acquiring his present magnificent train. We may, there- 

 fore, 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 trans- 

 mitted 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 eared pheasant ( Crossoptilon aicritum) 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 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 irrespectively 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 injuri- 

 ous to the females of these several allied species. 



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



