1885.] 



CLADOCEBA. 



15 



the obliquely curved posterior margins, a slight angular projec- 

 tion occurs. Viewed from below (fig. 1), the valves appear 

 strongly inflected along the ventral side, and provided at their 

 edges with long and delicate, inward bending bristles. At the 

 point, too, where, in a lateral aspect, the fore-mentioned angu- 

 lar projection occurs, is observed a very conspicuous emargina- 

 tion, causing the valves to be wide open in the posterior part, 

 even should their ventral parts be closely pressed together. The 

 posterior edges of the valves are armed in their inferior part (see 

 fig. 4) with a few strong denticles, succeeded by a very delicate 

 ciliation, which, however, disappears at about the middle of 

 their length. 



No sculpture whatever, neither on the carapace nor on the 

 shell of the head. 



The eye, placed in the frontal portion of the head, close 

 to its lower face, is comparatively large, and furnished with 

 numerous crystalline cones, forming a clear zone round the light, 

 brownish pigment. No trace of any ocular spot, or ocellus, can 

 be detected. 



The antennulæ do not exhibit any difference from those in 

 our northern species. 



The antennæ are, as usual, very powerfully developed, 

 though not of quite so remarkable a size as in D. brachyurum. 

 When reflexed (see fig. 2), they do not reach the posterior mar- 

 gin of the carapace, but for the rest fully agree in structure, 

 as also in the number and arrangement of the natatory setæ, 

 with our Northern forms. 



In regard to the oral parts and the branchial legs, those 

 organs would seem to be of precisely the same structure as in 

 the other known species. 



Also the terminal portion of the body, or tail (see fig. 3), 

 has a very similar form, being exceedingly short and conically 

 tapered, without any trace of anal denticles, whereas the apical 

 claws are very strong and armed at the base with 3 secondary 

 teeth. The caudal process is oblongo-mamilliform, and the two 



