The Descent of Man

the same sex, and accumulated through sexual
selection by attracting or exciting the females.
In many cases, however, such characters have
been transferred, either partially or completely,
to the females. In other cases, again, both sexes
have been coloured alike for the sake of protection;
but in no instance does it appear that the
female alone has had her colours or other characters
specially modified for this latter purpose.
The last point which need be noticed is that
fishes are known to make various noises, some
of which are described as being musical. Dr.
Dufosse, who has especially attended to this
subject, says that the sounds are voluntarily
produced in several ways by different fishes:
by the friction of the pharyngeal bones—by the
vibration of certain muscles attached to the
swim bladder, which serves as a resounding
board—and by the vibration of the intrinsic
muscles of the swim bladder. By this latter