140 



inner ramus very small, cylinclric in form, and carrying 2 minute setse on the 

 tip. 2nd pair of legs much smaller than the 1st and farther from the 

 median line, basal part less perfectly defined, though carrying outside the usual 

 bristle; outer ramus represented by a narrow oblong joint edged outside with 

 6 very minute and somewhat unequal bristles ; inner ramus reduced to a minute 

 conical process. 3rd pair of legs extremely small and rudimentary, being only 

 represented by a minute bisetose joint, without any accompanying bristle outside. 

 5th pair of legs likewise uniarticulate, but slightly larger than 3rd, and accom- 

 panied outside by the usual bristle. Ovisacs globular, projecting on each side, 

 and rather large, in some cases almost attaining the size of the whole body. 



Male very unlike the female in its outward appearance, and of much 

 more slender form of body. Cephalic segment occupying about half the total 

 length, and oval in outline, being scarcely as broad as it is long, lateral edges 

 evenly cuved, frontal part obtusely truncated. 2nd segment normally developed, 

 with the epimeral plates well defined and triangularly pointed behind. The 3 

 succeeding trunk-segments very small and narrow, not being at all expanded 

 laterally. Tail nearly half as long as the anterior division and composed of 5 

 well-defined segments, the 1st of which (the genital segment) is much the largest 

 and almost quadrate in outline, containing, as a rule, on each side a rounded 

 spermatophore; anal segment somewhat larger than the preceding one. Caudal 

 rami considerably more produced than in female, being more than twice as long 

 as they are broad, and slightly tapered distally; inner mediate seta very long, 

 attaining almost half the length of the body; the other setse comparatively 

 short. Anterior antennae much larger than in the female and composed of 10 well 

 defined joints, being not at all hinged, but provided with numerous delicate 

 sensory filaments curving backwards and especially densely crowded on the 1st 

 very large joint. Posterior antennae of exactly the same structure as in the female, 

 though somewhat less strong. Oral parts likewise very similar, except that the 

 maxillipeds are a little less robust. Legs, however, rather dissimilar, the 2 

 anterior pairs being much more fully developed and adapted for swimming. 1st 

 pair of legs with the basal part of normal appearance, and distinctly biarticulate; 

 outer ramus resembling in shape and armature that in female, but comparatively 

 larger and having the marginal setae distinctly ciliated ; inner ramus distinctly 

 biarticulate and nearly as long as the outer, proximal joint small, with a single 

 seta inside, distal joint oblong oval, and edged with 5 ciliated setae. 2nd pair 

 of legs quite normally developed, with both rami 3-articulate and armed in the 

 usual manner with spines and setse. 3rd pair of legs exhibiting exactly the same 

 rudimentary condition as in the female. Last pair of legs with the free joint 



