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well-marked transverse suture, indicating the boundary between the 1st trunk- 

 segment and the cephalon. The 3 succeeding segments gradually diminishing 

 in size, with the epimeral plates rounded off and, as a rule, discontiguous, 

 being separated by well-marked lateral incisions. Last trunk-segment very 

 small, not nearly as broad as the genital segment. Tail somewhat exceeding- 

 half the length of the anterior division; genital segment fully as long as the 

 3 succeeding segments combined, and having its anterior part considerably 

 dilated and rather sharply marked off from the posterior; anal segment not 

 attaining the length of the 2 preceding segments combined, and scarcely longer 

 than it is broad. Caudal rami of moderate length and sublinear in form, 

 equalling in length about the last 2 segments combined, and scarcely at all 

 divergent; seta of outer edge well marked and attached near the middle; 

 apical setae much reduced in size, the 2 middle ones terminating in a very 

 delicate smooth filament obtuse at the tip. Anterior antennae rather slender, 

 about equal in length to the cephalon, and clothed with scattered curved setae 

 of moderate length; 1st joint considerably dilated; 2nd joint about the length 

 of the 2 succeding joints combined; 4th joint longer than the 5th, which 

 equals the 6th in length; last joint very small. Posterior antennae moderately 

 strong, with the 2nd joint longer than the outer 2 combined; penultimate joint 

 short and very oblique, with 3 small bristles in front; terminal joint slightly 

 dilated in the middle and armed on the tip with 2 somewhat unequal claws, 

 the outer one shorter, but stronger, than the inner. Maxillae with the terminal 

 lappet very slender and finely ciliated on both edges, palp rather small, bisetose, 

 with a slight notch inside the tip. Anterior maxillipeds with the proximal 

 spinule of the apical lash much coarser than the others. Natatory legs with 

 the rami rather broad; terminal joint of the outer one carrying outside in the 

 2 anterior pairs 3, in the 2 posterior pairs 2 spines, those in the 1st pair 

 coarsely denticulate in front; terminal joint of inner ramus with only a single 

 spine in the 1st pair and 3 spines in the 2 succeeding pairs; inner ramus of 

 4th pair somewhat longer than the first 2 joints of the outer combined; distal 

 joint attenuated, with the apical spines rather slender. Last pair of legs ex- 

 tremely small, being represented on each side by a minute sub-cylindric joint 

 with 2 slightly unequal bristles on the tip. Ovisacs very large, extending far 

 beyond the end of the tail, and oblong, or nearly cylindric in form. 



Male of much smaller size than female, and having the anterior division 

 of the body less dilated. Tail, as usual, composed of 5 well-defined segments, 

 the foremost of which (the genital segment) is very large and tumid for the 

 reception of the 2 spermatophores. Posterior maxillipeds powerfully developed, 



