Chap. XY. LENGTH OF TAIL IN FEMALE. 165 



is now known ^ that she "enters the nest head first, 

 " and then turns round with her tail sometimes over 

 " her back, but more often bent round by her side. 

 '* Thus in time the tail becomes quite askew, and is a 

 " tolerable guide to the length of time the bird has 

 been sitting." Both sexes of an Australian kingfisher 

 (Tanysi^tera sylvia) have the middle tail-feathers greatly- 

 lengthened ; and as the female makes her nest in a 

 hole, these feathers become, as I am informed bv Mr. 

 E. B. Sharpe, much crumpled during nidification. 



In these two 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 pre- 

 vented through natural selection. Judging from these 

 cases, if with the peahen, the development of the tail 

 had been checked only when it became inconveniently 

 or dangerously long, she would have acquired a much 

 longer tail than she actually possesses ; for lier 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 develop- 

 ment was consequently checked, slie would have con- 

 tinually reacted on her male progeny, and thus have 

 prevented the peacock from acquiring his present mag- 

 nificent train. 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. 



' Mr. Kamsay, in ' Proc. Zoolog. Sec' 18G8, p. 50. 



