The Descent of Man

tation of the males become at once intelligible
by the aid of sexual selection.
We have next to inquire whether this view of
the bright colours of certain male fishes having
been acquired through sexual selection can,
through the law of the equal transmission of
characters to both sexes, be extended to those
groups in which the males and females are brilliant
in the same, or nearly the same degree
and manner. In such a genus as Labrus, which
includes some of the most splendid fishes in the
world—for instance, the Peacock Labrus (L.
pavo), described (28. Bory Saint Vincent, in
'Dict. Class. d'Hist. Nat.' tom. ix. 1826, p. 151.),
with pardonable exaggeration, as formed of
polished scales of gold, encrusting lapis-lazuli,
rubies, sapphires, emeralds, and amethysts—
we may, with much probability, accept this
belief; for we have seen that the sexes in at least
one species of the genus differ greatly in colour.
With some fishes, as with many of the lowest