Chap. XV. 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 
{Tanysiptera 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 by Mr. 
B. 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 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 develop- 
ment was consequently checked, she 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. 
^ My. Kamsay, in ‘Proc. Zoolog. Soc.' 1868, p. 50. 
