CALIGID^E. 
263 
The parts corresponding to the foot-jaws are well de- 
veloped. They are three pairs. The first pair (t. XXXIV, 
f. 5 c ) — the posterior antennae of Kroyer — is situate be- 
tween the siphon and antennae, and consists of two articu- 
lations ; the basal broad and fleshy, the terminal tapering 
to the extremity, which is in form of a strong hook. 
At a little distance from, and external to, the extremity 
of this joint, we see a stout, horny-looking, hooked spine, 
springing from it. The second pair (t. XXXIV, f. 5 h) 
is longer than the preceding, and consists of two articu- 
lations ; the basal more slender than that of the first pair, 
and the terminal still more so, of considerable length, and 
ending in two or three falciform claws, the edges of w T hich 
are armed with small teeth. The third pair (t. XXXIV, 
f. 5 i) is longer than the two preceding, though not 
so long as the second. It is cheliform, and differs a 
little in the two sexes. In the male, it consists of a 
large, fleshy, basal joint, which has articulated to it a 
stout claw, curved inwards, and having a small seta near 
its apex. In the female, the basal joint is smaller, and 
less fleshy, and the terminal is longer and larger than in 
the male. These foot-jaws constitute real organs of pre- 
hension, and it is by means of them that the animal 
fastens itself upon its prey. 
The true feet, or natatory feet, consist of four pairs, 
three of which are attached to the thoracic segment of the 
carapace, while the fourth springs from the penultimate 
ring of the thorax. The first pair (t. XXXIV, f. 5 k) has 
three articulations. The basal joint is of a cylindrical 
form, and the second is similar in size and form, but with 
numerous very short setae on under margin. The third, 
or terminal, is about one half the size of the others, and 
has on its inferior edge three long, finely-ciliated setae, 
nearly as long as the preceding joint of the leg, and at 
the apex four short, stout, naked setae. The second pair 
(t. XXXIV, f. 5 1) is composed of two basilar joints, the 
first short, and provided with a long ciliated seta on its 
under surface ; the second very large, becoming broader 
