ORDER DECAPODA — PLATYCARCINUS. 



separated from this a closely allied species, which he thinks has been confounded by Say 

 himself with the preceding, supposing one to be the male and the other the female. It ap- 

 pears to have a wide geographical range, for Mr. Randall (Jour. Acad. Nat. Sc. Vol. 8) 

 has noticed it on the northwest coast of North America. 



Platycarcinus sayi. 



Cancer irroralut. Say, Jour. Acad. Nat. Sc. partly. Vol. 1, p. 60, pi. 4, fig. 2. 

 C. sayi. Gould, Invertebrata of Massachusetts, p. 322. 



Description. Shield smooth, less convex and more angular at the sides than in the preceding. 

 The teeth on the antero-lateral margins nine, pointed, smooth, not denticulated. Legs longer 

 in proportion than the preceding ; the thighs of the second and third pair greatly exceeding 

 the margin of the shield. Lines on the external part of the hand not conspicuously granu- 

 lated. Abdominal segment of the male broader than in the preceding species. 



Color, yellow, doited with dark purplish brown. Finger and thumb scarcely dark colored ; 

 bend of the wrist and inner face of the hand bright rose-red. 



Length, 2" 75. Transverse diameter, 4'0. 



This species was first separated from the preceding by Drs. Gould and Binney, and has 

 been observed on this coast. According to Dr. Gould, it is common on rocky bottoms, and 

 is brought in considerable numbers to market. 



GENUS PILUMNUS. Leach. 



Shield arched in front. Feet of the first pair unequal. The second joint of the external an- 

 tennas lodging in the internal canthus of the orbit, and the antennae extending beyond the 

 margin of the shield. In other respects, resembling Xanthus. 



PlLUMNUS HARRISI. 



PLATE VII. FIG. 15. 

 Pilumnus harrisi. Gould, Invertebrata of Mass. p. 326. 



Description. Shield quadrilateral, narrowed backwards, rounded before, rectilinear behind 

 and at the sides. Three triangular teeth at the sides ; eyes distant ; orbits oval, with a fissure 

 over the centre ; front divided by a fissure into two lobes. Surface very minutely granulated, 

 and hispid with very short hairs, which entangle the dirt : there are three or four broken 

 series of curved transverse lines or ridges rising into little crests. Limbs slender, cylindrical. 

 Carpus with a projecting angle in front. Hands robust, smooth, and with a double line along 



