7
MALE AND FEMALE CRAYFISHES.
backwards with rapid jerks, propelled by the strokes of a broad, fan-shaped flipper, wThich terminates the hinder end of the body (fig. 1, t, 20).
In front of the four pairs
of legs, which are used in walking, there is a pair of limbs of a much more massive character, each of which ends in two claws disposed in such a manner as to constitute
a
powerful
pincer
claws are
the chief weapons of
10).
These
offence and
defence
(fig. 1;
of the crayfish, and those who handle them incautiously will discover that their grip is by no means to be des¬ pised, and indicates a good deal of disposable energy. A sort of shield covers the front part of the body, and ends in a sharp projecting spine in the middle line (?’).
On each side of this is an eye, mounted on a
movable stalk (I), which can be turned in any direction: behind the e}Tes follow two pairs of feelers ; in one of these, the feeler ends in two, short, jointed filaments {2) ; while, in the other, it terminates in a single, many-jointed filament, like a whip-lash, which is more than half the length of the body (3).
Sometimes turned backwards,
sometimes sweeping forwards, these long feelers con¬ tinually exjfiore a considerable area around the body of the crayfish. If a number of cravfishes, of about the same size, are compared together, it will easily be seen that they fall into two sets ;
the jointed tail being much broader,
especially in the middle, in the one set than in the other (fig. 2).
The broad-tailed crayfishes
are
the
