I20 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



Genus GEOGRAPSUS Stimpson 



The characters of this genus are given in the synopsis, page loi 

 [47]. It is sufficiently distinguished from Grapsus proper, in which 

 it is incUided by Milne Edwards, not only by its terrestrial habits 

 (which seem to have been hitherto unknown), but also in the shorter, 

 thicker body, shorter suborbital lobes, smaller antennse, and the 

 smoothly rounded inferior extremity of the meros- joint of the walk- 

 ing feet. 



196. GEOGRAPSUS RUBIDUS ' Stimpson 



Plate XVI, Fig. 3, 3a 



Geograpsus rubidus Stimpson, Proc. Acad. Nat. Sci. Phila.. x, p. 103 

 [49], 1858. 



Carapax moderately convex, widening considerably immediately 

 behind the second lateral tooth, so that the sides are anteriorly con- 

 vex and posteriorly slightly concave. Proportion of length to 

 breadth, i : 1.17. Transverse striae sharp, both anteriorly and pos- 

 teriorly. Anterior gastric lobules sufficiently prominent. Frontal 

 margin rather strongly crenulated. Surface of the meros-joint of 

 the outer maxillipeds conspicuously striated. Meros-joint of chel- 

 ipeds broad, with seven generally equal teeth on its anterior margin. 

 Upper surface of hand obliquely striated, striae tuberculated. Lower 

 surface of hand marked with strong, regular, somewhat distant 

 striae. Ambulatory feet sparsely provided with long setae ; the meros 

 very thin and much dilated ; dactyli as long as or longer than the 

 penult joint. 



In life the carapax is of a deep red or mahogany color above, 

 shining, becoming rather yellowish or orange toward the margins. 

 Feet paler. Hands often yellow. Color beneath yellowish-white. 

 Dimensions of the carapax in a male: Length, 1.12; breadth, 1.31 

 inches. 



This species is allied to G. crinipcs Dana, in its long dactyli. but 

 may be distinguished by its more convex sides and the stronger and 

 more distant striae on the inferior surface of the hand. 



It was found on Peel Island, one of the Bonin group, in October. 

 It usually occurred among damp leaves or under stones, most fre- 

 quently along the banks of mountain streams. It was sometimes 

 found near the seashore, and occasionally at great elevations. 



^Geograpsus grayi (Milne Edwards). 



