S. I. Smith on Ainerican Crustacea. \73 



tion or emarsijination, and is continuous with the lateral margin of the 

 buccal area, which is broad behind as in the Pinnotherldm. The pal- 

 ate is not divided longitudinally either by lateral ridges or even by a 

 median one, so that the efferent passages are not distinctly separated 

 at their external orifices. 



In the external maxillipeds, the ischium is coaleseent with the 

 merus as in the Pinnotheridce, and the palpus is composed of only 

 two segments, of Avhich the terminal one is large and spatulate. 



The chelipeds are small and equal and the hands short and rounded. 



The ambulatory legs are small and slender and the dactyli in the 

 three anterior pairs are short and deeply bifurcate, while those of the 

 posterior pair are simple and slender. 



In the male, the sternum is flat and very broad, the breadth between 

 the posterior legs being much more than twice as great as the breadth 

 of the basal segments of the abdomen. 



The male abdomen is narrow and only three-jointed, the first and 

 second segments anchylosing into one piece, the third, fourth, fifth, 

 and sixth into another, and the terminal being free. The verges are 

 sternal and the appendages of the first segment are large and stout, 

 while those of the second segment are very small. 



Dissodactylus nitidus, sp. nov. 



Male. The carapax is broad posteriorly, the breadth at the poste- 

 rior margin being but little less than that between the lateral angles, 

 and the postero-lateral margins are about as long as the antero-lateral. 

 The dorsal surface is naked and polished, and is slightly convex in 

 front and along the lateral margins, but flat in the middle and poste- 

 riorly. The antero-lateral border is slightly arcuate and is armed 

 with an upturned margin which curves suddenly inward at the lateral 

 angle, and extends a third of the way to the middle of the carapax. 

 The postero-lateral border is nearly straight and is armed with a slight 

 upturned margin. 



The merus in the external maxillipeds is of about equal width at 

 base and summit, the inner and outer margins are nearly straight, and 

 the angles at the summit are rounded. The segments of the palpus 

 are quite long, and, when folded down, the tip reaches to the anterior 

 margin of the sternum ; the terminal segment is spatulate and its dis- 

 tal end quite broad and squarely truncated. 



In the chelipeds, the merus extends but little beyond the margin of 

 the carapax; the carpus is short, smooth, and unarmed; the hands 

 are smooth, rounded, somewhat swollen, and the fingers are slender 



