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 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
Soemmerring 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 injurious to the females of these several
allied species.
We may now consider Mr. Wallace s arguments in regard to the sexual
coloration of birds. He believes that the bright tints originally
acquired through sexual selection by the males would in all, or almost
all cases, have been transmitted to the females, unless the
transference had been checked through natural selection. I may here
remind the reader that various facts opposed to this view have already
been given under reptiles, amphibians, fishes and lepidoptera. Mr.
Wallace rests his belief chiefly, but not exclusively, as we shall see
in the next chapter, on the following statement (9. Journal of
Travel, edited by A. Murray, vol. i. 1868, p. 78.), that when both
sexes are coloured in a very conspicuous manner, the nest is of such a
nature as to conceal the sitting bird; but when there is a marked
contrast of colour between the sexes, the male being gay and the female
dull-coloured, the nest is open and exposes the sitting bird to view.
This coincidence, as far as it goes, certainly seems to favour the
belief that the females which sit on open nests have been specially
modified for the sake of protection; but we shall presently see that
there is another and more probable explanation, namely, that
conspicuous females have acquired the instinct of building domed nests
oftener than dull-coloured birds. Mr. Wallace admits that there are, as
might have been expected, some exceptions to his two rules, but it is a
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