colours or markings when the
species is observed in a museum or in a menagerie, are often highly
protective when the creature is seen under the natural conditions of its
existence. From these varied classes of facts it seems not improbable
that fully one-half of the species in the animal kingdom possess colours
which have been more or less adapted to secure for them concealment or
protection.

Passing onward we find the explanation of a distinct type of colour or
marking, often superimposed upon protective tints, in the importance of
easy recognition by many animals of their fellows, their parents, or
their mates. By this need we have been able to account for markings that
seem calculated to make the animal conspicuous, when the general tints
and well-known habits of the whole group demonstrate the need of
concealment. Thus also we are able to explain the constant symmetry in
the markings of wild animals, as well as the numerous cases in which the
conspicuous colours are concealed when at rest and only become visible
during rapid motion. In striking contrast to ordinary protective
coloration we have "warning colours," usually very conspicuous and often
brilliant or gaudy, which serve to indicate that their possessors are
either dangerous or uneatable to the usual enemies of their tribe. This
kind of coloration is probably more prevalent than has been hitherto
supposed, because in the case of many tropical animals we are quite
unacquainted with their special and most dangerous enemies, and are also
unable to determine whether they are or are not distasteful to those
enemies. As a kind of corollary to the "warning colours," we find the
extraordinary phenomena of "mimicry," in which defenceless species
obtain protection by being mistaken for those which, from any cause,
possess immunity from attack. Although a large number of instances of
warning colour and of mimicry are now recorded, it is probably still an
almost unworked field of research, more especially in tropical regions
and among the inhabitants of the ocean.

The phenomena of sexual diversities of coloration next engaged our
attention, and the reasons why Mr. Darwin's theory of "sexual
selection," as regards colour and ornament, could not be accepted were
stated at some length, together with the theory of animal coloration and
ornament we propose to substitute for it. This theory is held to be in
harmony with the general facts of animal coloration, while it enti