Pjecilopoda. 143 



tremity of the middle one, and common to both pieces of the shell, 

 two small, closely approximated, simple eyes(l); these carinse are 

 armed with teeth or acute tubercles. The duplicature of this shell 

 at its anterior extremity, beneath, forms a level border, strongly 

 arcuated, and terminated inferiorly by a double arc, projecting like 

 a tooth towards the centre of union. Immediately under this pro- 

 jection, in the cavity of the shield, is a small inflated labrum, cari- 

 nated in the middle and terminating in a point, above which are in- 

 serted two little antennae, in the form of small didactyle forceps, flexed 

 into an elbow in the middle of their length, at the point of union be- 

 tween the first joint and the second, or of the forceps properly so 

 styled. Directly beneath, inserted and approximated by pairs, and 

 on two lines, are twelve feet, the ten first of which, the two or four 

 anterior ones of the males excepted, terminate in a didactyle forceps; 

 their radical joint, projecting inwards like a lobe and covered with 

 points, performs the office of a jaw. The size of these feet augments 

 progressively; those of the fifth pair excepted, they are all composed 

 of six joints, the movable toe of the forceps included. The latter 

 have an additional joint, and also differ from the preceding ones by 

 having, at their external base, a bi-articulated appendage, directed 

 backwards, the last joint of which is compressed and obtuse; by 

 their fifth joint being terminated on the inner side by five small, 

 movable, horny, narrow, elongated and pointed leaflets, and by the 

 two toes of the forceps being movable or articulated at base. The 

 two pieces situated between these feet, which M. Savigny considers 

 as the ligula, appear to me to be merely two maxillary lobes of these 

 organs, but detached or free. The pharynx occupies the interval 

 included by all these feet. The males are distinguished from the 

 females by the form of the forceps, which terminate the two or four 

 anterior feet: they are inflated and deprived of the movable toe. The 

 two last feet of this shield are united in the form of a large, mem- 

 branous, and almost semi-circular leaflet, having the sexual organs 

 on its posterior face, and presenting, in the middle of an emargina- 

 tion of the posterior margin, two small triangular, elongated and 

 pointed divisions, which appear to represent the internal toes of the 

 forceps; the other articulations are indicated by sutures. The se- 

 cond piece of the shell, articulated with the first in the middle of its 

 posterior emargination and filling the interval it forms, is nearly 

 triangular, and is angularly truncated and emarginated at its poste- 

 rior extremity. Its lateral edges are alternately emarginated and 

 dentated, and in the middle of each of the emarginations, counting 



(1) One on each side of the tooth that terminates this carina. 



