1'2> CALIFORNIA ACADEMY OF SCIENCES. 



thin, unarmed, about as wide as long, concave above, very strongly curved 

 externally, the upturned inner margin somewhat irregular and nearly 

 straight. The ischium of the maxillipeds is small, trigonal, the outer 

 angle furnished with a small tooth; of the two edges which face the middle 

 line, the inner one is the longer and finely denticulated, the outer one is 

 furnished with two rounded teeth; the merus is smooth, flattened, 

 strongly produced at the outer angle, the inner and outer margins sharp, 

 the outer surface transversely concave; the joints of the palp are strongly 

 compressed and crested above. Chelipeds stout; inner margin of the 

 ischium acute; inner margin of the merus with a compressed (occasion- 

 ally subconical) tooth; the carpus has a ridge on the outer surface, an 

 acute projecting distal margin, and a tooth over the upper' hinge joint 

 of the hand; hands smooth, compressed, with a single, rounded, longi- 

 tudinal ridge a little below the middle of the outer surface; the high 

 upper crest is produced at the distal end; fingers short and stout, 

 dactyl with a superior crest which is most prominent at the proximal 

 end. Ambulatory legs smooth, naked, strongly compressed, with the 

 upper edges acute; the lower side of the merus is flattened, not deeply 

 grooved as in typicus; the acute inferior margin of the propodi ends dis- 

 tally in a short spine; dactyls spinulous below, about three-fourths the 

 length of the propodi. The sides of the abdomen in the male are nearly 

 straight, but in the female they are convex and more or less unequal; the 

 basal joint is nearly vertical, with a depression on either.side of the cen- 

 ter; the posterior side more strongly concave in the female than in the 

 male; the sutures of the median and lateral pieces alternate, those between 

 the lateral pieces being transverse in the male but oblique on one side in 

 the female, the penultimate segment is oblong, distally widened, and 

 -concave at the distal end; the telson is very small and fits into the space 

 between the bases of the chelipeds. 



Length of Carapace. Width of Carapace. 

 Male 47 mm 64 mm. 



" 36 mm 53 mm. 



" 35 mm 50 mm. 



" 32 mm 47 mm. 



" 16 mm 23 mm. 



Female 36.5 mm 49.5 mm. 



" 25 mm 36 mm. 



The males I have seen in a fresh condition were all of 

 a uniform, bright red color. Two females seen were 

 red but with a purplish tinge irregularly marked with 

 blotches of a lighter color. This species is often seen at 

 low tide on the sides of rocks where, at some distance, 



