having a rufous thorax.), which I saw in Mr. Bates s collection, are
generally redder but rather duller than the females, the latter being
coloured of a more or less splendid golden-green. On the other hand, in
one species the male is golden-green, the female being richly tinted
with red and purple. In the genus Esmeralda the sexes differ so greatly
in colour that they have been ranked as distinct species; in one
species both are of a beautiful shining green, but the male has a red
thorax. On the whole, as far as I could judge, the females of those
Prionidae, in which the sexes differ, are coloured more richly than the
males, and this does not accord with the common rule in regard to
colour, when acquired through sexual selection.
[Fig.16. Chalcosoma atlas. Upper figure, male (reduced); lower figure,
female (nat. size).
Fig. 17. Copris isidis.
Fig. 18. Phanaeus faunus.
Fig. 19. Dipelicus cantori.
Fig. 20. Onthophagus rangifer, enlarged. (In Figs. 17 to 20 the
left-hand figures are males.)]
A most remarkable distinction between the sexes of many beetles is
presented by the great horns which rise from the head, thorax, and
clypeus of the males; and in some few cases from the under surface of
the body. These horns, in the great family of the Lamellicorns,
resemble those of various quadrupeds, such as stags, rhinoceroses,
etc., and are wonderful both from their size and diversified shapes.
Instead of describing them, I have given figures of the males and
females of some of the more remarkable forms. (Figs. 16 to 20.) The
females generally exhibit rudiments of the horns in the form of small
knobs or ridges; but some are destitute of even the slightest rudiment.
On the other hand, the horns are nearly as well developed in the female
as in the male Phanaeus lancifer; and only a little less well developed
in the females of some other species of this genus and of Copris. I am
informed by Mr. Bates that the horns do not differ in any manner
corresponding with the more important characteristic differences
between the several subdivisions of the family: thus within the same
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