give as an additional instance the Calotes maria, which at this season
has a bright red head, the rest of the body being green. (72. Gunther
in Proceedings, Zoological Society, 1870, p. 778, with a coloured
figure.)
Both sexes of many species are beautifully coloured exactly alike; and
there is no reason to suppose that such colours are protective. No
doubt with the bright green kinds which live in the midst of
vegetation, this colour serves to conceal them; and in N. Patagonia I
saw a lizard (Proctotretus multimaculatus) which, when frightened,
flattened its body, closed its eyes, and then from its mottled tints
was hardly distinguishable from the surrounding sand. But the bright
colours with which so many lizards are ornamented, as well as their
various curious appendages, were probably acquired by the males as an
attraction, and then transmitted either to their male offspring alone,
or to both sexes. Sexual selection, indeed, seems to have played almost
as important a part with reptiles as with birds; and the less
conspicuous colours of the females in comparison with the males cannot
be accounted for, as Mr. Wallace believes to be the case with birds, by
the greater exposure of the females to danger during incubation.
CHAPTER XIII.
SECONDARY SEXUAL CHARACTERS OF BIRDS.
Sexual differences Law of battle Special weapons Vocal
organs Instrumental music Love-antics and dances Decorations, permanent
and seasonal Double and single annual moults Display of ornaments by
the males.
Secondary sexual characters are more diversified and conspicuous in
birds, though not perhaps entailing more important changes of
structure, than in any other class of animals. I shall, therefore,
treat the subject at considerable length. Male birds sometimes, though
rarely, possess special weapons for fighting with each other. They
charm the female by vocal or instrumental music of the most varied
kinds. They are ornamented by all sorts of combs, wattles,
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