erally
of a rich semi-transparent brown, banded with black and yellow; Methona
is of large size, the wings transparent like horn, and with black
transverse bands; while the delicate Ithomias are all more or less
transparent, with black veins and borders, and often with marginal and
transverse bands of orange red. These different forms are all copied by
the various species of Leptalis, every band and spot and tint of colour,
and the various degrees of transparency, being exactly reproduced. As if
to derive all the benefit possible from this protective mimicry, the
habits have become so modified that the Leptalides generally frequent
the very same spots as their models, and have the same mode of flight;
and as they are always very scarce (Mr. Bates estimating their numbers
at about one to a thousand of the group they resemble), there is hardly
a possibility of their being found out by their enemies. It is also
very remarkable that in almost every case the particular Ithomias and
other species of Heliconidae which they resemble, are noted as being very
common species, swarming in individuals, and found over a wide range of
country. This indicates antiquity and permanence in the species, and is
exactly the condition most essential both to aid in the development of
the resemblance, and to increase its utility.

But the Leptalides are not the only insects who have prolonged their
existence by imitating the great protected group of Heliconidae;--a genus
of quite another family of most lovely small American butterflies, the
Erycinidae, and three genera of diurnal moths, also present species which
often mimic the same dominant forms, so that some, as Ithomia ilerdina
of St. Paulo, for instance, have flying with them a few individuals of
three widely different insects, which are yet disguised with exactly the
same form, colour, and markings, so as to be quite undistinguishable
when upon the wing. Again, the Heliconidae are not the only group that
are imitated, although they are the most frequent models. The black and
red group of South American Papilios, and the handsome Erycinian genus
Stalachtis, have also a few who copy them; but this fact offers no
difficulty, since these two groups are almost as dominant as the
Heliconidae. They both fly very slowly, they are both conspicuously
coloured, and they both abound in individuals; so that there is every
reason to believe that they possess a protection of a similar kind to
the Helic