tion may probably be accounted for by the fact
that these birds do not need the protection of a less conspicuous
colour. They are very pugnacious, and often attack and drive away crows,
hawks, and kites; and as they are semi-gregarious in their habits, the
females are not likely to be attacked while incubating.

2. Orioles (Oriolidae). The true orioles are very gay birds; the sexes
are, in many Eastern species, either nearly or quite alike, and the
nests are open. This is one of the most serious exceptions, but it is
one that to some extent proves the rule; for in this case it has been
noticed, that the parent birds display excessive care and solicitude in
concealing the nest among thick foliage, and in protecting their
offspring by incessant and anxious watching. This indicates that the
want of protection consequent on the bright colour of the female makes
itself felt, and is obviated by an increased development of the mental
faculties.

3. Ground thrushes (Pittidae). These elegant and brilliantly-coloured
birds are generally alike in both sexes, and build an open nest. It is
curious, however, that this is only an apparent exception, for almost
all the bright colours are on the under surface, the back being usually
olive green or brown, and the head black, with brown or whitish stripes,
all which colours would harmonize with the foliage, sticks, and roots
which surround the nest, built on or near the ground, and thus serve as
a protection to the female bird.

4. Grallina Australis. This Australian bird is of strongly contrasted
black and white colours. The sexes are exactly alike, and it builds an
open clay nest in an exposed situation on a tree. This appears to be a
most striking exception, but I am by no means sure that it is so. We
require to know what tree it usually builds on, the colour of the bark
or of the lichens that grow upon it, the tints of the ground, or of
other surrounding objects, before we can say that the bird, when sitting
on its nest, is really conspicuous. It has been remarked that small
patches of white and black blend at a short distance to form grey, one
of the commonest tints of natural objects.

5. Sunbirds (Nectarineidae). In these beautiful little birds the males
only are adorned with brilliant colours, the females being quite plain,
yet they build covered nests in all the cases in which the nidification
is known. This is a negative rather than a positive exception to the
rule, since th