52 
ZOOLOGY OF THE VOYAGE OF H.M.S. SAMARANG. 
2. CHASMAGNATHUS, Be Ham. 
1. CHASMAGNATHUS CONVEXUS, Be Ram. 
Thorace gibbo, granulato, brevi-setoso, dorso subtetragono, lateribus arcuato. 
Fronts arcuata, medio sinuatA 
Hab. Maria orientalia. 
Oclypode ( Chasmagnathus ) convexa, De Haan, E. 1. p. 56. t. 7. f. 5. 
Carapace gibbose, granulated, shortly-setose, subtetragonal on the back, arched at the 
sides. 
Front arcuated, sinuated in the middle. 
Hab. Eastern Seas. 
VIII. GRAPSIDJE. 
The Sesarmce are found in various localities, sometimes in fresh-water rivulets, among 
weeds ; sometimes under damp logs and stones at a considerable distance from any water, 
and most frequently among the roots of mangroves in salt-water swamps. They are active 
and extremely wary in their habits, and, like the Grapsi, very predacious. The Grapsus plicatm 
is a very common species in Borneo, and appears to vary greatly in colour according to the 
localities in which it is found. The Grapsi are fond of rocks, over which they run with 
surprising agility ; they frequently remain stationary for hours, basking in the sun, when 
the tide has just left the high rocks. 
1. UTICA, White. 
Pedipalpi externi articulo tertio externe recto non dilatato. 
Thorace 8-angulato, depresso, post-medium caring transversa valde distincta ; margine latero-anteriore 
dentibus tribus ; parte latero-posteriore obliqua, parte posteriore recta. 
Chelis parvis. 
Pedibus posterioribus perlongis, tarso vix dilatato subelongato, pilis ihnbriato. 
Outer jaw-feet with the third joint, on the outside, straight, not dilated. 
Carapace somewhat eight-angled, tabular, a very strong transverse ridge behind the 
middle ; latero-anterior margin with three teeth ; latero-posterior part oblique, posteriorly 
very straight. 
Fore-legs small. 
Hind -legs very long, tarsus not particularly dilated, somewhat elongated, fringed with 
hairs as is the preceding joint. 
This genus is nearly allied to Trichopus , De Haan, which is synonymous with Varuna, 
M. Edwards. 
