On Fresh-wat&r Crvstacea. By Robert Gurnet/. 293 



upper lip and of the post-abdomen being identical. The sculpture 

 is certainly variable, and may be present in Asiatic individuals. 

 Specimens from Calcutta which I have examined show a reticula- 

 tion which, though faint, is as distinct as that of many of my 

 specimens from Algeria. D. negUcta Daday is only distinguish- 

 able from this species by a slight prominence in the anterior 

 margin of the upper lip, and in this respect forms a transition to 

 D. odontoplax Sars, in which the anterior margin is provided with a 

 tooth-like projection. 



D. crassa was found to be abundant in a pond in Biskra, which 

 I call the " frog pond," by reason of the multitude of frogs living 

 in it. 



Cyclops planvs sp. n. — Female : Body flattened and tapering 

 gradually without any abrupt transition between thorax and 

 abdomen. Segments of the thorax separated by rather deep inden- 

 tations (plate XII. fig. 24). The first abdominal segment broad, as 

 long as the remaining segments together ; the furcal rami about as 

 long as the last two segments of the abdomen together. The pro- 

 portional lengths of the furca and its setae may be expressed thus — 



Furca 20 



Set?e : — Outermost . . . . . . . . 11 



„ 2nd 33 



„ 3rd .,. ..104 



4th 8 



The lateral setae are inserted about the middle of the furca. 

 The first pair of antennae (plate XII. fig. 27) short, reaching 

 about half-way along the first segment of the thorax, and consisting 

 of nine segments only. The proportional lengths of the joints are 

 as follows : — 



Length .. 11 64354345 

 Joints .. 123456789 



The third joint is partially divided into two : the sixth joint, 

 corresponding to the 12th-14th of the 17-jointed antenna, bears a 

 sensory club. 



All the swimming legs have both branches 2-jointed ; the last 

 joint of the exopodite of the third leg bears three lateral spines 

 and one terminal spine, while the last joint of the endopodite has 

 a single terminal spine (plate XII. fig. 26). The last joint of the 

 exopodite of the fourth leg has two lateral and one terminal spine. 

 The fifth leg (plate XII. fig. 25) consists of a single cylindrical 

 joint armed with a minute spine and a long terminal seta. The 

 egg-sacs are closely pressed to the abdomen and contain few eggs. 

 The form of the receptaculum seminis is not clearly distinguish- 

 able, but appears to consist of an elongated oval sac with two 



