284 
BRITISH ENTOMOSTRACA. 
plates, and springing immediately from beneath their 
terminal point, we see the antennae. These are very 
small, and consist of two short, simple articulations. 
The structure of the mouth is also very similar to that 
of the Caligidae, consisting of a sucking-tube, inclosed 
within a sheath, and one pair of rudimentary organs at- 
tached to its sides, equivalent to the jaws. The style of 
the sucking-tube is longer and more slender than in 
Caligus, and there is only one pair of rudimentary organs, 
representing the first pair of jaws, the smaller and more 
external pair being wanting. The foot-jaws are three 
pairs. The first differ from the corresponding pair of the 
Caligidae, in having at their base a large fleshy-looking 
lobe, and in wanting the horny-looking, hooked spine 
which springs from near its base. The second and third 
are similar in structure to the corresponding pairs of the 
Caligi ; but we see no trace of what has been described in 
them as the sternum. 
The feet are four pairs, and are attached to the different 
segments of the thorax. The three first pairs are short, 
divided into two stalks, each consisting of two or three 
flat joints, which are beset with short cilia. The basilar 
joint in each foot, from which the two stalks spring, shows 
much the same form as that in the Caligi. The fourth 
pair of feet differs from the others considerably. Instead 
of the two stalks being small, jointed, and armed with 
setae, they are each of only one joint, and that large, mem- 
branous, of an oval shape, and not possessing any setae or 
hairs on their margin at all. 
On the under surface of the last segment of the thorax, 
very near where it articulates with the abdomen, there is 
a small forked, horny body, which M. Edwards considers 
as a rudimentary fifth pair of feet. 
