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

RBESEMBLANCES.AMONG ANIMALS. 107
strong, pugnacious, noisy, and very abundant Tropidorhynchus.
Miy friend, Mr. Osbert Salvin, has given me another
interesting case of bird mimicry. In the neighbourhood of Rio Janeiro is found an insect-eating hawk
(Harpagus diodon), and in the same district a birdeating hawk (Accipiter pileatus) which closely resembles it. Both are of the same ashy tint beneath,
with the thighs and under wing-coverts reddish brown,
so that when on the wing and seen from below they
are undistinguishable. The curious point, however, is
that the Accipiter has a much wider range than the
Harpagus, and in the regions where the insect-eating
species is not found, it no longer resembles it, the under
wing-coverts varying to white; thus indicating that
the red-brown colour is kept true by its being useful
to the Accipiter to be mistaken for the insect-eating
species, which birds have learnt not to be afraid of.
3Mimicry among Mfammals.
Among the Mammalia the only case which may be
true mimicry is that of the insectivorous genus Cladobates, found in the Malay countries, several species
of which very closely resemble squirrels. The size is
about the same, the long bushy tail is carried in the
same way, and the colours are very similar. In this
case the use of the resemblance must be to enable the
Cladobates to approach the insects or small birds on
which it feeds, under the disguise of the harmless fruiteating squirrels