PACHYCHELES PANAMENSIS. 71 
PACHYCHELES Srimrs. 
Proc. Acad. Nat. Sci. Phila., X. 228, 1858. 
Pachycheles panamensis Fax. 
Plate XV, fig: 22 
Bull. Mus. Comp. Zo6l., XXIV. 175, 1893. 
Carapace subcircular, the longitudinal and transverse diameters nearly 
equal, upper surface flattened, granulate and setose, especially on the gastric 
and anterior portion of the branchial regions, posterior portions of the 
branchial regions lightly rugose. Front broad, produced to a rounded 
median lobe, lateral portions straight, inner orbital angle rounded, not pro- 
duced ; outer orbital angle projecting as a triangular tooth between the eye 
and the base of the antenna. Lateral border of the carapace with a con- 
cavity behind the antenna; the margin is slightly raised as a rim which is 
lost in one of the branchial rugs before reaching the hind border of the cara- 
pace ; hind border slightly concave. Chelipeds unequal, the right being 
the larger; upper surface of the merus rugose and setose, under surface 
smooth, internal distal angle produced as a denticulated tooth ; carpus short 
and broad, upper surface tuberculous and setose, internal border armed with 
a large tooth at the base, followed by one or two smaller teeth, lower surface 
smooth and naked; upper surface of the propodite furnished with small 
tubercles which bear stiff bristles, inner margin rounded, not toothed, outer 
margin granulated, lower syface convex, naked and polished near the centre 
(where the surface is reticulated in the larger claw), squamoso-granular and 
setose near the edges; fingers gaping, crossing at tips, toothless on both the 
inner and outer margins (or at most slightly denticulated on the outer mar- 
gin). Ambulatory appendages setose. 
Length of carapace, 6.5 mm., breadth, 7 mm.; breadth of frontal margin, 
2 mm. 
Panama, March 12. 1 fem. ovig. 
Pachycheles rudis Stimps. is a larger species, with the posterior margin of 
the carapace more concave (the concavity having almost the shape of a trian- 
gular notch); the carapace and chelipeds are less setose than in P. panamensis, 
the anterior margin of the carpus not prominently toothed, and there is a 
strong protuberance near the middle of the upper surface of the propodite. 
In P. tuberculipes Lockington the central part of the front is triangular and 
