stick while the insect is supported by the middle pair of
legs, which are not noticed among the twigs and fibres
that surround it. The head and antennae are drawn back
between the wings so as to be quite concealed, and there
is a little notch hollowed out at the very base of the
wings, which allows the head to be retracted sufficiently.
All these varied details combine to produce a disguise
that is so complete and marvellous as to astonish every
one who observes i t ; and the habits of the insects are
such as to utilize all these peculiarities, and render them
available in such a manner as to remove all doubt of
the purpose of this singular case of mimicry, which is
undoubtedly a protection to the insect. Its strong and
swift flight is sufficient to save it from its enemies when
on the wing, but if it were equally conspicuous when at
rest it could not long escape extinction, owing to the
attacks of the insectivorous birds and reptiles that abound
in the tropical forests. A very closely allied species,
Kallima inachis, inhabits India, where it is very common,
and specimens are sent in every collection from the
Himalayas. On examining a number of these, it will be
seen that no two are alike, but all the variations correspond
to those of dead leaves. Every tint of yellow, ash, brown,
and red is found here, and in many specimens there occur
patches and spots formed of small black dots, so closely
resembling the way in which minute fungi grow on leaves
that it is almost impossible at first not to believe that
fungi have grown on the butterflies themselves !
If such an extraordinary adaptation as this stood alone,
it would be very difficult to offer any explanation of i t ; but
although it is perhaps the most perfect case of protective
imitation known, there are hundreds of similar resemblances
in nature, and from these it is possible to deduce
a general theory of the manner in which they have been
slowly brought about. The principle of variation and that
of “ natural selection,” or survival of the fittest, as elaborated
by Mr. Darwin in his celebrated “ Origin of Species,
offers the foundation for such a theory; and I have myself
endeavoured to apply it to all the chief cases of imitation
in an article published in the Westminster Review for 1867,
entitled, “Mimicry, and other Protective Resemblances
anionw Animals,” to which any reader is referred who
wishes to know more about this subject.
In Sumatra, monkeys are very abundant, and at Lobo
Raman they used to frequent the trees which overhang
the guard-house, and give me a fine opportunity of
observing their gambols. Two species of Semnopithecus
were most plentiful—monkeys of a slender form, with very
long tails. Not being much shot at they are rather bold,
and remain quite unconcerned when natives alone are
present; but when I came out to look at them, they would
stare for a minute or two and then make off. They take