Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

RESEMBLANCES AMONG ANIMLIES. 99
constantly on the search for crickets with which to
provision their nests.
Perhaps the most wonderful case of all is the large
caterpillar mentioned by Mr. Bates, which startled him
by its close resemblance to a small snake. The first
three 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.
Cases of Mlimicry among the Vertebrata.
flaving thus shown how varied and extraordinary
are the modes in which mimicry occurs among insects,
we have now to enquire if anything of the same kind
is to be observed among vertebrated animals. When
we consider all the conditions necessary to produce a
good deceptive imitation, we shall see at once that such
can very rarely occur in the higher animals, since they
possess none of those facilities for the almost infinite
modifications of external form which exist in the very
nature of insect organization. The outer covering of
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