NO. 1401. J'ABASrnC COJ'J'JPOIJS— CALK ilD.E— WILSON. 653 



Free segment short and narrow, overlapped by the carapace ante- 

 riorly and by the genital segment posteriorly. From either side of 

 this segment there projects over the base of the fourth leg a narrow, 

 blunt plate or spine, about half as long as the basal joint of the leg. 

 This overl3ang plate, together with the small size of the fourth legs, 

 renders the latter invisible in dorsal view. 



Genital segment transversely semilunar in shape, one-third wider 

 than long, the sides well rounded, the posterior angles prolonged 

 backward as stout bhmt lobes. The posterior margin ])etween these 

 lobes is deeply concave, being fully one-third of the entire length. 

 The fifth legs are not visible dorsally, but may be distinctly seen upon 

 the ventral surface of the p(jsterior lobes. The abdomen is so small 

 as to be at least partially rudimentary. It is less than one-fourth the 

 width of the genital segment and does not quite reach the level of the 

 tips of the posterior lobes of the genital segment. In shape it is 

 ovate, the base being contracted strongly and joining the genital seg- 

 ment on its ventral surface, a little anterior to its posterior margin. 

 The genital segment thus overlaps and partially conceals the base of 

 the abdomen. 



The anal larainge are proportionally of good size, but armed with 

 small setffi. Egg cases about two-thirds as long as the body, and con- 

 siderably wider than the abdomen, each containing thirty-five to forty 

 eggs. 



Of the appendages the anterior antennpe are short, the two joints 

 about the same length and not very heavily armed with seta? and spines. 

 Second antennse small and without any accessory spine at the base of 

 the proximal joint. 



First maxillffi large and well curved, but with very little swelling at 

 the base. Second pair simple, with a wide triangular base and a short 

 blunt tip; they are attached opposite the base of the mouth tube and 

 extend slightly beyond its tip. 



The mouth tube is short and evenly rounded, nearly as wide as it is 

 long. First maxillipeds of the usual form; second pair very small and 

 weak, hardly larger than the first pair; the terminal claw is a little 

 more than half the length, and considerably less than half the width, 

 of the basal joint. 



The tiny accessory spine is attached close to the distal end of the 

 claw on the inner margin. 



The first swimming legs are smaller than usual, with only one of the 

 three terminal claws at all developed, the other two being rudimentary. 

 The plumose setaj on the posterior ))order of the terminal joint, how- 

 ever, are full size. 



The exopod of the second legs has but two spines; the one on the 

 first joint is large and stout, but the one on the second joint is rudi- 

 mentary. The rami of the third legs are large and well separated, 



Proc. N. M. vol. xxviii— 04 42 



