140 S. I. Smith ou Anierlcan Crustacea. 



near the lateral margin. The upper edge of the superior orbital 

 border is sinuous and the border itself is quite narrow. The antero- 

 lateral angles are sharp and project prominently forward. The 

 inferior orbital margin is thin and sharply dentate and its outer angle 

 is jDrominent and angular, and is separated from the superior margin 

 by a deep and broadly rounded sinus. 



In the larger cheliped, the merus is slender, and its anterior surface 

 is narrow and smooth and the mai'gins are unarmed and rounded. 

 The carpus is evenly rounded and nearly smooth externally. The 

 basal portion of the propodus is smooth or microscopically granu- 

 lose and flat and entirely unarmed within ; the depression into 

 wliich the carpus folds is very short, not extending half way to the 

 base of the dactylus ; and the superior and inferior margins are evenly 

 rounded. The propodal finger is slightly upturned at the tip, the 

 inferior edge is perfectly smooth and evenly rounded, and the tuber- 

 cles of the prehensile edge are nearly obsolete except a large de- 

 pressed one near the middle. The dactylus is strongly curved down- 

 ward at tip, the superior edge is smooth and rounded and the pre- 

 hensile edge is obscurely tubercular In very young specimens the 

 hand is quite granulose above but becomes smooth with age. 



In the smaller cheliped the tips of the fiugers are densely clothed 

 with soft hair. 



The ambulatory legs are slender, smooth and almost entirely naked. 



The females differ from the males in the carapax being a little 

 narrower in proportion, and in the branchial regions being slightly 

 inflated and more granular or even tuberculose. 



Several specimens give the following measurements : — 



C. — Species in which the fourth, fifth and sixth segmtnts of the male abdomen completely 

 anchylose, and in which the carapax is very transverse, and the branchial regions are 

 gibbons. 



Gelasimns gibbosns, sp- nov. 



Plate II, figure 11. Plate IV, figure 8. 



Male. This is a small species quite different in general appearance 

 from any of the foregoing. The body is very short and broad, very 



