segments behind the head were dilatable at
the will of the insect, and had on each side a large black pupillated
spot, which resembled the eye of the reptile. Moreover, it resembled a
poisonous viper, not a harmless species of snake, as was proved by the
imitation of keeled scales on the crown produced by the recumbent feet,
as the caterpillar threw itself backward!

The attitudes of many of the tropical spiders are most extraordinary and
deceptive, but little attention has been paid to them. They often mimic
other insects, and some, Mr. Bates assures us, are exactly like flower
buds, and take their station in the axils of leaves, where they remain
motionless waiting for their prey.

I have now completed a brief, and necessarily very imperfect, survey of
the various ways in which the external form and colouring of animals is
adapted to be useful to them, either by concealing them from their
enemies or from the creatures they prey upon. It has, I hope, been shown
that the subject is one of much interest, both as regard a true
comprehension of the place each animal fills in the economy of nature,
and the means by which it is enabled to maintain that place; and also as
teaching us how important a part is played by the minutest details in
the structure of animals, and how complicated and delicate is the
equilibrium of the organic world.

My exposition of the subject having been necessarily somewhat lengthy
and full of details, it will be as well to recapitulate its main
points.

There is a general harmony in nature between the colours of an animal
and those of its habitation. Arctic animals are white, desert animals
are sand-coloured; dwellers among leaves and grass are green; nocturnal
animals are dusky. These colours are not universal, but are very
general, and are seldom reversed. Going on a little further, we find
birds, reptiles and insects, so tinted and mottled as exactly to match
the rock, or bark, or leaf, or flower they are accustomed to rest
upon--and thereby effectually concealed. Another step in advance, and we
have insects which are formed as well as coloured so as exactly to
resemble particular leaves, or sticks, or mossy twigs, or flowers; and
in these cases very peculiar habits and instincts come into play to aid
in the deception and render the concealment more complete. We now enter
upon a new phase of the phenomena, and come to creatures whose colours
neither conceal them nor make them like vegetable