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 setz 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 proximal 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 sets 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 short, 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 sete. Length of carapace, 6.3 mm.; breadth, 13 mm. 
Panama, March 12. 4 males, 6 fem. ovig. 
