the head to behind the eyes, and on the forehead forms a
little double crest of scaly feathers, which adds much to
the vivacity of the bird’s aspect. The bill is gamboge
yellow, and the iris blackish olive. (Figure at p. 3 5 3 .)
The female of this species is of a tolerably uniform
coffee-brown colour, but has a blackish head, and the nape,
neck, and shoulders yellow, indicating the position of the
brighter colours of the male. The changes of plumage
follow the same order of succession as in the other species,
the bright colours of the head and neck being first developed,
then the lengthened filaments of the tail, and last of
all, the red side plumes. I obtained a series of specimens,
illustrating the manner in which the extraordinary black
tail ribands are developed, which is very remarkable.
They first appear as two ordinary feathers, rather shorter
than the rest of the ta il; the second stage would no doubt
be that shown in a specimen of Paradisea apoda, in which
the feathers are moderately lengthened, and with the, web
narrowed in the middle; the third stage is shown by a
specimen which has part of the midrib bare, and terminated
by a spatulate web; in another the bare midrib is a little
dilated and semi-cylindrical, and the terminal web very
small; in a fifth, the perfect black horny riband is formed,
but it bears at its extremity a brown spatulate web, while
in another a portion of the black riband itself bears, for a
portion of its length, a narrow brown web. It is only
after these changes are fully completed that the red side
plumes begin to appear.
The successive stages of development of the colours and
plumage of the Birds of Paradise are very interesting, from
the striking manner in which they accord with the theory
of their having been produced by the simple action of
variation, and the cumulative power of selection by the
females, of those male birds which were more than .usually
ornamental. Variations of colour are of all others the
most frequent and the most striking, and are most easily
modified and accumulated by man’s selection of them.
We should expect, therefore, that the sexual differences of
colour would be those most early accumulated and fixed,
and would therefore appear soonest in the young birds;
and this is exactly what occurs in the Paradise Birds. Of
all variations in the form of birds’ feathers, none are so
frequent as those in the head and tail. These occur more
or less in every family of birds, and are easily produced in
many domesticated varieties, while unusual developments
of the feathers of the body are rare in the whole class of
birds, and have seldom or never occurred in domesticated
species. In accordance with these facts, we find the scale-
formed plumes of the throat, the crests of the head, and
the long cirrhi of the tail, all fully developed before the
plumes which spring from the side of the body begin to
make their appearance. If, on the other hand, the male