260 
THE VOYAGE OF H.M.S. CHALLENGER. 
An adult male from Port Jackson measures : — 
Length of carapace, . 
Breadth of carapace, nearly, . 
Adult d • 
Lines. Millims. 
6 13 
8J 17-5 
Geograpsus, Stimpson. 
Geograpsus, Stimpson, Proc. Acad. Nat. Sci. Philad., p. 101, 1858. 
„ Kingsley, Proc. Acad. Nat. Sci. Philad., p. 195, 1880. 
Discoplax, A. Milne Edwards, Ann. Soc. Entom. France, ser. 4, vol. vii. p. 284, 1867; Nouv. 
Archiv. Mus. Hist. Nat., vol. is. p. 293, 1873. 
Orthograpsus, Kingsley, Proc. Acad. Nat. Sci. Philad, p. 194, 1880. 
This genus is allied to Leptograpsus and to Pachygrapsus, but is distinguished 
from both by the form of the carapace, which is depressed, plicated only near the 
lateral margins, with the antero-lateral margins straight or arcuated only at the hepatic 
regions, posteriorly nearly straight ; they are armed with a single tooth behind the 
exterior orbital tooth. Front of moderate width and deflexed. The orbits, epistoma, buccal 
cavity, post-abdomen, and eye-peduncles present nothing remarkable. The basal antennal 
joint is short and but slightly produced at its antero-external angle. As in Grapsus, the 
endognathi of the exterior maxillipedes are narrow ; the merus-joints, in particular, 
slender and elongated, distally truncated, and bearing the next joint at or near the 
antero-external angle. The chelipedes and ambulatory legs resemble those of Lepto- 
grapsus and P achy grapsus, but the fingers of the palms of the chelipedes are acute or 
subacute, not excavated at the distal extremities. 
The species occur both in the Indo-Pacific and Atlantic regions, and are all, I believe, 
littoral or shallow- water forms. 
The genus Discoplax is united by Kingsley with Geograpsus, but may prove to be 
distinct in the figure of the type ( Discoplax longipes, A. Milne Edwards), the carapace 
is represented as strongly arcuated and granulated anteriorly, and the merus of the 
exterior maxillipedes is shorter and broader than in the typical Geograpsi. 
The species of Geograpsus as restricted above are : — 
Geograpsus lividus, Milne Edwards ( = Geograpsus brevipes, Milne Edwards; 
Geograpsus occidentalis, Stimpson). West Indies; California; Chili. 
Geograpsus crinipes, Dana ( = Geograpsus depressus, Heller, fide Kingsley). 
Polynesian Islands. 
Geograpsus longitarsis (Dana). Paumotu Archipelago. 
Geograpsus grayi, Milne Edwards ( = Geograpsus rubidus, Stimpson). Indo- 
Pacific Eegion. 
