1818.] CRUSTACEA OF THE UNITED STATES. 239 



raised into an angle on the tnicldle of the lower edge and 

 incurved at base; carpus trilateral, granulated, not con- 

 cave, at base beneath projected into a prominent angle 

 or hook, which on the hind edge is furnished with a few 

 short stout hairs, superior edge simply emarginace near 

 the base; hand very much elongated, sublinear, compres 

 sed, glabrous, two -jointed, first joint a little contracted 

 towards the base, not broader than half the length of the 

 carpus, second joint equal in breadth to, and, excepting 

 the fingers, two thirds the length of the preceding joint; 

 fingers more than half as long as the preceding joint, with 

 fasciculated hairs, thumb rectilinear at base, decurved at 

 tip and armed with a strong, truncated tooth behind the 

 middfe, finger unarmed, incurved; second pair of feet 

 with the third joint obtriangular, equal at tip to the base 

 of the fourth, which, with the thumb and finger, is tri- 

 angular, terminal joints deeply ciliated; third pair with 

 the penultimate joint transverse, attached to the preced- 

 ing one by the middle of the base, deeply ciliated and 

 terminated at the superior tip by a very small joint, which 

 is rounded at base and acute at X\\>\ fourth dcaA fifth pairs 

 somewhat cylindrical, terminal joints comose, thumb and 

 projecting angle or finger concealed by the hair; abdomen 

 of six segments, two anterior ones membranaceous, the 

 first narrowed to the base, supported on each side, and at 

 the tip beneath, by a semicrustaceous rib, with a linear 

 appendage at each of the hind angles beneath, the second 

 segment supported on each side by a vitreous scale, and 

 at base beneath by an angular semicrustaceous rib, with 

 linear appendices as in the preceding segment; third, 

 fourth and fifth segments semicrustaceous, octangular, 

 subequal; sixth segment subquadrate, narro\^ ed behind 



