iven at page 101, or at page 89 of the first edition,
for I have long entertained this view, though I have never had space to
develop it. But I had not sufficient knowledge to generalise as far as
you do about colouring and nesting. In your paper perhaps you will just
allude to my scanty remark in the fourth edition, because in my Essay
on Man I intend to discuss the whole subject of sexual selection,
explaining as I believe it does much with respect to man. I have
collected all my old notes, and partly written my discussion, and it
would be flat work for me to give the leading idea as exclusively from
you. But, as I am sure from your greater knowledge of Ornithology and
Entomology that you will write a much better discussion than I could,
your paper will be of great use to me. Nevertheless I must discuss the
subject fully in my Essay on Man. When we met at the Zoological Society,
and I asked you about the sexual differences in kingfishers, I had this
subject in view; as I had when I suggested to Bates the difficulty about
gaudy caterpillars, which you have so admirably (as I believe it will
prove) explained. (429/2. See a letter of February 26th, 1867, to Mr.
Wallace, "Life and Letters" III., page 94.) I have got one capital case
(genus forgotten) of a [Australian] bird in which the female has long
tail-plumes, and which consequently builds a different nest from all her
allies. (429/3. Menura superba: see "Descent of Man" (1901), page 687.
Rhynchoea, mentioned a line or two lower down, is discussed in the
"Descent," page 727. The female is more brightly coloured than the male,
and has a convoluted trachea, elsewhere a masculine character. There
seems some reason to suppose that "the male undertakes the duty of
incubation.") With respect to certain female birds being more brightly
coloured than the males, and the latter incubating, I have gone a little
into the subject, and cannot say that I am fully satisfied. I remember
mentioning to you the case of Rhynchoea, but its nesting seems unknown.
In some other cases the difference in brightness seemed to me hardly
sufficiently accounted for by the principle of protection. At the
Falkland Islands there is a carrion hawk in which the female (as I
ascertained by dissection) is the brightest coloured, and I doubt
whether protection will here apply; but I wrote several months ago to
the Falklands to make enquiries. The conclusion to which I have been
leaning is that in some of the