protection afforded by them. And so we find a deceptive similarity
between animals occurring in the same district, but not closely
related, in which the mimicked form is unpalatable or has an odour
repulsive to birds and lizards. It must, of course, be understood
that the mimicry is unconscious, the result, as in the cases of
cryptic resemblance, having been brought about by natural
selection--the less perfect the mimicry the more liable are the
individuals to be attacked, and the less chance have they of
reproducing their kind.

This imitation was first accounted for by Mr. Bates in the case of
the Heliconidae, a group of showy, slow-flying abundant butterflies
possessing "a strong pungent semi-aromatic or medicinal odour which
seems to pervade all the juices of their system." It does not
follow, of course, that what seems to us a disagreeably smelling
fluid should prove distasteful to the palate of a lizard or a bird.
But careful observation of the butterflies convinced both Bates and
Wallace that they were avoided, or at any rate not pursued, by
birds and other creatures; and Belt found that they were rejected
by his tame monkey which was very fond of other insects. So their
conspicuous wings, with spots and patches of yellow, red, or white
upon a black, blue or brown ground, may fairly be considered an
example of warning colouration--though Mr. Thayer has with great
ingenuity and acumen endeavoured to show that the markings are
effective for concealment and that their value as warning marks is
doubtful. Now, says Mr. Beddard, "in the same situations as those
in which the Heliconias are found there also occur, more rarely,
specimens of butterflies minutely resembling the Heliconias, but
belonging to a perfectly distinct family--the Pieridae. They belong
to the two genera Leptalis and Euterpe, consisting of numerous