The Descent of Man

llic and iridescent. Circular spots are sometimes
surrounded by one or more differently shaded
zones, and are thus converted into ocelli. Nor
need much be said on the wonderful difference
between the sexes of many birds. The common
peacock offers a striking instance. Female birds
of paradise are obscurely coloured and destitute
of all ornaments, whilst the males are probably
the most highly decorated of all birds, and
in so many different ways that they must be
seen to be appreciated. The elongated and golden-orange
plumes which spring from beneath
the wings of the Paradisea apoda, when vertically
erected and made to vibrate, are described
as forming a sort of halo, in the centre of which
the head "looks like a little emerald sun with its
rays formed by the two plumes." (73. Quoted
from M. de Lafresnaye in 'Annals and Mag. of
Natural History,' vol. xiii. 1854, p. 157: see also
Mr. Wallace's much fuller account in vol. xx.
1857, p. 412, and in his 'Malay Archipelago.'S)
In another most beautiful species the head is