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CHAPTER XXX 
INTERSEXUAL SELECTION 
sy all the birds which I have enumerated as having 
a bright or pleasingly coloured mouth cavity, 
acquired, as I believe, through the agency of 
sexual selection, the sexes are alike, both in regard 
to this special feature, and also in their plumage 
and general appearance. They are alike also in 
their habit of opening and shutting the bill, as 
it were, at one another, and in their other nuptial 
actions or antics. The first of these two identities 
involves no difficulty. In many birds of bright 
plumage the female is as gaudy, or almost as gaudy, 
as the male, and it is then assumed (by those, at 
least, who follow Darwin) that each successive 
variation in the hue and markings of the latter has, 
by the laws of inheritance, been transmitted in an 
equal or only slightly less degree to the former. As 
far, therefore, as the particular kiad of beauty which 
I am here considering is, in itself, concerned, the 
arguments for or against its acquirement by the male, 
through the choice of the female, are the same as 
in regard to that of any other kind, nor do they 
- extend any farther; but in the display of it by the 
female as well as by the male a fresh element enters 
into the problem, as it does also in the case of any 
other nuptial display common to the two sexes. 
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