148 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



243. RHYNCHOPLAX MESSOR Stimpson 



Rhynchoplax mcssor Stimpson, Proc. Acad. Nat. Sci. Phila., x, p. 109 

 [55], 1858. 



In this species the carapax is sufficiently indurated. The propor- 

 tion of breadth to length in the male specimen described is 1:1.1. 

 Carapax triangular, somewhat convex ; surface smooth but uneven, 

 with a few scattered setae. Gastric and cardiac regions somewhat 

 protuberant ; branchial regions often depressed. Lateral teeth small 

 but sharp and prominent. Median tooth of the rostrum flattened, 

 spatuliform, equaling in length about one-fifth that of the carapax 

 and pointing obliquely upward. Chelipeds claviform, sparsely 

 setose ; meros with four or five teeth on the superior edge ; carpus 

 with three or four small blunt teeth above ; hand smoothly rounded, 

 with one very small tooth on the middle of the upper side ; inner 

 surface about the bases of the fingers thickly lanose. Ambulatory 

 feet slender, each joint dentigerous at the middle and at the outer 

 extremity, with the exception of the dactyli which are of moderate 

 length, and strongly sickle-shaped. 



Color purplish-brown and yellowish, variegated. Dimensions of 

 the carapax: Length, 0.241 ; breadth, 0.22; length of cheliped, 0.42; 

 of first pair of ambulatory feet, 0.455 inch. 



This crab, like all others of the family, dies when placed in spirits 

 in such a state of brittle rigidity, with feet outstretched and easily 

 separated, that it is almost impossible to preserve a perfect speci- 

 men. 



It was taken at Simoda, at low-water mark. 



244. RHYNCHOPLAX SETIROSTRIS Stimpson 



Rlivnchoplax sctirostris Stimpson, Proc. Acad. Nat. Sci. Phila., x, p. 109 

 ' [55], 1858. 



Description of a female : Carapax but little indurated, ovate, flat- 

 tened ; proportion of breadth to length, 1:1.08. Surface nearly 

 smooth ; sparsely and inconspicuously setose. Regions sufficiently 

 distinct about the middle, separated by linear sulci. Lateral margins 

 of the dorsum raised ; posterior-lateral tooth spiniform, sharply 

 prominent ; anterior tooth not prominent. Dorsal margin distinct 

 across the base of the rostrum. Median tooth of rostrum styliform, 

 slender and setose ; lateral teeth extremely slender and sharp. 

 Chelipeds weak ; meros with a tooth at the summit ; hand slender ; 

 fingers as long as the palm. Ambulatory feet very slender, minutely 



