in the Museum of the Smithsonian Institution. 99 



the body, and terminates posteriorly in a strongly projecting angle. 

 The postero-lateral margins are slightly concave, and form a very 

 obtuse angle -wdth each other on account of the little projection of the 

 intestinal region. The periphery is armed with teeth, which are short, 

 triangular, and regularly approximated on the antero-lateral and 

 outer latei-al margins, but are longer, more spiniform, and irregularly 

 arranged on the postero-lateral margins. On the iipper surface, 

 besides the usual depression between the cardiac and branchial regions, 

 there are four deep excavations in front of the latter region ; — two 

 separating it from the hepatic, and two, somewhat larger, from the 

 gastric region. There is also a deep concavity on the frontal region, 

 which is continued posteriorly for a short distance on the gastric 

 region. The rostrum is large, regularly triangular, and deflexed to a 

 right angle with the general level of the gastric region ; inai'gin un- 

 armed, or only obscurely toothed. The surface of the protuberant 

 parts of the carapax is covered w4th low, granulated tubercles. The 

 chelipeds are much shorter and stouter than in the typical forms of the 

 genus, and are deeply concave above, the concavity being smooth or 

 nearly so, and defined by prominent marginal crests, which, except 

 on the carpus, are strongly toothed. The meros-joint of the chelijDed 

 is particulai'ly short ; its anterior crest is armed with three or four 

 teeth, and' its superior one wjth only two large teeth, the outer one 

 of which is much the largest. In the hand, the crest of the superior 

 margin is armed with six unequal, approximated, triangular teeth ; 

 and that of the outer margin with two conical distant teeth, besides 

 the knob at each extremity. The lower surface of the hand is orna- 

 mented with four or five rows of granulated tubercles, those of the 

 middle row being largest and most conspicuous; inner margin ser- 

 rated with granulated teeth. Ambulatory feet much compressed, and 

 crested above. In the female abdomen each segment is armed with 

 short setose tubercles, there being a larger ridge-like one, equalling in 

 extent the length of the joint, in the middle, and four or five small 

 ones on each side. 



Length of the carapax in a female, 1.20; breadth, 1.38 inch; pro- 

 portion 1:1.15; length of meros-joint of cheliped, 0.G8 ; length of 

 greater hand, 1.20 inch. 



