1887.] 



ON CYCLESTHERIA HISLOPI. 



23 



this lobe, partly crossing its apical part on the posterior side, 

 and forming* together a densely crowded comb-like fan. projecting 

 from the lobe and curved npwards and forwards. This lobe. 

 found in all the forms belunging to the present group of Plyllopoda. 

 has most properly been termed the maxillary process, exhibiting. 

 as it does, a very striking resemblance to the first pair of 

 maxillæ. The fonr succeeding lobes project far less and are 

 obtusely truncate at the end, the upper one being the broadest. 

 They are each provided with a dense series of very delicate and 

 «lender posteriorly pointing setæ, arranged in a comb-like manner, 

 and originating side by side, close together. at some distance 

 from the free edge of the lobes. along the posterior surface of 

 the leg (see Pl. V. fig. 1). The free edge of the lobes protruding 

 on the anterior side. over the bases of the above-mentioned setæ 

 {see fig. 2), is slightly imdnlated, and exhibits another series of 

 setæ, which, however, are considerably shorter and far less nu- 

 merons. Moreover, at the bases of the three npper lobes occur, 

 on the anterior side, a nnmber of råtner short spiniform bristles, 

 arranged in separate gronps, four or five in each group (see fig. 

 2). The penultimate lobe is somewhat narrower than the pre- 

 ceding and more prominent, especially on the first pair of legs 

 (Pl. IV, figs. 7, 8), and the marginal setæ point more obliquely 

 down w ard. The terminal lobe, representing the last segment of 

 the endopodite, has in the embryo much the same appearance as 

 the preceding (see Pl. VII, fig. 6. TY), whereas in the adult 

 animal (see Pl. IV. figs. 7, 8, Pl. V. figs. 1, 2) it forms a rather 

 large and somewhat expanded plate, pointing straight downward, 

 and obliquely rounded at the end, which is provided with a single 

 row of setæ, increasing successively in length toward the inner 

 more projecting angle. 



The epipodite, apparently issuing from the outer side of the 

 second segment of the stem, has on all the legs the form of a rather 

 small oblong sac-like appendage, pointing upwards and apparently 

 corresponding to the podobranchiæ in higher Crustacea. 



The exopodite, originating immediately below the epipodite. 

 from the outer side of the third segment of the endopodite, is 



