The Descent of Man

in colour between the sexes. It is further manifest,
in all the cases in which the males take
exclusive charge of the nests and young, that
the destruction of the brighter-coloured males
would be far more influential on the character
of the race, than the destruction of the brightercoloured
females; for the death of the male during
the period of incubation or nursing would
entail the death of the young, so that they could
not inherit his peculiarities; yet, in many of these
very cases the males are more conspicuously
coloured than the females.
In most of the Lophobranchii (Pipe-fish, Hippocampi,
etc.) the males have either marsupial
sacks or hemispherical depressions on the abdomen,
in which the ova laid by the female are
hatched. The males also shew great attachment
to their young. (39. Yarrell, 'History of British
Fishes,' vol. ii. 1836, pp. 329, 338.) The sexes do
not commonly differ much in colour; but Dr.
Gunther believes that the male Hippocampi are