species, each of which shows a striking likeness to some one
particular species of Heliconia. This likeness is not a mark of
near affinity; it affects no important character, but only the
shape and colouration of the wings."

The particular resemblance here described was the origin of the
theory of Protective Mimicry, the conditions under which it occurs
being, according to Mr. Wallace:

1. That the imitative species occur in the same area and occupy
the same station as the imitated.
2. That the imitators are always the more defenceless.
3. That the imitators are also less numerous in individuals.
4. That the imitators differ from the bulk of their allies.
5. That the imitation, however minute, is external and visible
only, never extending to internal characters or to such as do
not affect the external appearance.

There are plenty of examples of this phenomenon, such as the
hornet-like moths and bee-like flies of our own country, and many
other instances will be found in these pages. One discovered in
tropical America by Mr. W.L. Sclater would have much delighted Belt
had he come across it. In that region of the world the leaf-cutting
ants present a very characteristic appearance as the column
proceeds homewards, each ant carrying a piece of leaf held
vertically in its jaws; and a homopterous insect has been found
that faithfully resembles an ant bearing its burden. The latter is
suggested by the thin compressed green body of the insect, and its
profile is precisely like that of the jagged edge of the fragment
of leaf held over the back of the ant.