BRITISH ENTOMOSTRACA. 



plates, and springing immediately from beneath their 

 terminal point, we see the antennas. 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 slyl.e 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. Kdwards considers 

 as a rudimentary fifth pair of feet. 



