qual protection. The snow-bunting, the jer-falcon, and the
snowy owl are also white-coloured birds inhabiting the arctic regions,
and there can be little doubt but that their colouring is to some extent
protective.

Nocturnal animals supply us with equally good illustrations. Mice, rats,
bats, and moles possess the least conspicuous of hues, and must be quite
invisible at times when any light colour would be instantly seen. Owls
and goatsuckers are of those dark mottled tints that will assimilate
with bark and lichen, and thus protect them during the day, and at the
same time be inconspicuous in the dusk.

It is only in the tropics, among forests which never lose their foliage,
that we find whole groups of birds whose chief colour is green. The
parrots are the most striking example, but we have also a group of green
pigeons in the East; and the barbets, leaf-thrushes, bee-eaters,
white-eyes, turacos, and several smaller groups, have so much green in
their plumage as to tend greatly to conceal them among the foliage.

_Special Modifications of Colour._

The conformity of tint which has been so far shown to exist between
animals and their habitations is of a somewhat general character; we
will now consider the cases of more special adaptation. If the lion is
enabled by his sandy colour readily to conceal himself by merely
crouching down upon the desert, how, it may be asked, do the elegant
markings of the tiger, the jaguar, and the other large cats agree with
this theory? We reply that these are generally cases of more or less
special adaptation. The tiger is a jungle animal, and hides himself
among tufts of grass or of bamboos, and in these positions the vertical
stripes with which his body is adorned must so assimilate with the
vertical stems of the bamboo, as to assist greatly in concealing him
from his approaching prey. How remarkable it is that besides the lion
and tiger, almost all the other large cats are arboreal in their
habits, and almost all have ocellated or spotted skins, which must
certainly tend to blend them with the background of foliage; while the
one exception, the puma, has an ashy brown uniform fur, and has the
habit of clinging so closely to a limb of a tree while waiting for his
prey to pass beneath as to be hardly distinguishable from the bark.

Among birds, the ptarmigan, already mentioned, must be considered a
remarkable case of special adaptation. Another is a South-American
goatsucker (C