20 



ovaries generally of a bright blue. The inferior antennse of the male 

 are large organs,, somewhat flattened in shape, broad at the base, 

 toothed at about two-thirds of their length on the external edge, and 

 becoming narrower near the extremity, which presents an appearance 

 as if somewhat bifurcated. Those of the female are much shorter, 

 cylindrical, and pointed at the extremity. The two antenniform 

 appendages arising from near the base of these organs in the male 

 are of considerable length, longer than the antennse themselves, and 

 filiform. The front of the head is prolonged into a prominence 

 which is cleft down the centre and forked. The feet are long, com- 

 posed of three joints, all of which are nearly of equal size, and have 

 their edges beset with numerous short hairs or setae, which when 

 magnified are finely plumose. The caudal fins are of considerable 

 size, flat and plumose. The male organs are slender and rather long. 



2. Branchipus SPiNOSus, M. Edwards. Antennis inferiorihus 

 maris magnis, cylindricis, apice acuminatis ; appendicibus an- 

 tenniformibus curtis, crassis ; abdominis segmentis infra spini- 

 feris. 

 Long. 1 poll. 2 lin. 



Branchipus spinosus, M. Edwards, Hist. Nat. Crust, iii. 367. 

 Hab. In lacu salino " Hadjibe," in vicinitate urbis Odessse ; M. 

 Nordmann. 



This species, which was discovered by Professor Nordmann in a 

 salt lake near Odessa, is upwards of an inch in length. The inferior 

 antennse of the male are large, cylindrical, the terminal articulation 

 being sharp at the point. They possess no tooth or process, and the 

 antenniform appendages are very short compared with those of the 

 preceding species, and of a considerable degree of thickness. The 

 front of the head has no prolongation. The feet are short. The seg- 

 ments of the abdomen are armed underneath with sharp spines, and 

 the caudal fins are short and plumose. The male organs are short 

 and obtuse. 



Genus Streptocephalus. 



Corpus cylindricum, segmentum caudate pinnis duabus ciliatis in- 

 structum ; pedes undecim ; antennce inferiores maris triarticu- 

 latce, valde tortuoscB, ad apicem in ramos graciles divisce, ap- 

 pendicibus antenniformibus armatce. 

 In the structure of the body, abdomen, and feet, this genus re- 

 sembles entirely the preceding. The inferior antennse, or cephalic 

 horns, in the male, however, are very difl'erent in structure ; they 

 are longer in proportion than the corresponding organs in the Bran- 

 chipus, consist of three articulations, and are singularly twisted, and 

 bent as it were into elbows. The terminal joint divides at the apex 

 into two branches. They are inhabitants of fresh water. Only two 

 species have as yet been described, and I now add a third to the 

 number. 



1 . Streptocephalus torvicornis, Waga. Antennis inferiori- 

 bus maris validis, ramis terminalibus elongatis, serratis, interna 



