PINNIXA PANAMENSIS. 31 



shoulder, back of which the carapace diminishes abruptly in width. A trans- 

 verse depression involves the hind part of the gastric and the fore part 

 of the cardiac regions. This depression is bounded behind by a ridge 

 which extends across the carapace between the bases of the last pair 

 of thoracic appendages. Back of this ridge the carapace is deflected at an 

 angle of about forty-five degrees. Front depressed, divided by a median 

 notch into two not prominent lobes ; margin setose. The chelipeds are 

 small, with very stout carpus and hand, destitute of spines, but furnished 

 with some setse along their edges ; carpus squamose on the anterior and 

 superior parts of the outer side ; propodus not broader than the carpus, 

 laterally compressed ; a row of tubercles along the superior border forms a 

 sort of crest ; a longitudinal row of setiferous squamoid tubercles runs 

 lengthwise of the hand from the pi'oximal end, stopping short of the base 

 of the immobile finger ; the surface between this and the dorsal crest is 

 thickly beset with tubercles, but below it the surface is almost smooth down 

 to a row of tubercles which runs along the inferior margin ; immovable finger 

 straight, the dactylus closing against it throughout its length ; dactylus fur- 

 nished with long sette on the upper margin ; no prominent teeth or tubercles 

 on the cutting edge of either finger. First and second ambulatory limbs of 

 moderate length, nearly naked, with slender and straight dactyli ; last three 

 segments tuberculate on superior margin. Third pair very much enlarged ; 

 the merus has a convex anterior border, and is pubescent on the anterior 

 third of the upper surface ; posterior margin double, spinulose. Fourth 

 ambulatory legs very small, not reaching beyond the distal end of the merus 

 of the third pair; upper surface smooth. Dactyli of penultimate and last 

 pairs of legs sliort, acute, set at angle with the propodi so as to form pre- 

 hensile hooks. End joint of abdomen broader than the preceding joint, 

 semicircular. The dactylus of the outer maxillipeds articulates with the 

 propodus near the distal end of the latter. The carapace is 5 mm. long by 

 10 mm. broad. 



The female is larger than the male, the carapace is more highly polished, 

 the transverse depression not so pronounced, and the appendages are more 

 thickly clothed with setJB. Length of carapace, 6.3 mm.; breadth, 13 mm. 



Panama, March 12. 4 males, 6 fem. ovig. 



