52 ZOOLOGY OF THE VOYAGE OE H.M.S. SAMARANG. 



2. CHASMAGNATHUS, De Haan. 



1. CHASMAGNATHUS CONVEXUS, Be Haan. 



Tkorace gibbo, granulato, brevi-setoso, dorso subtetragono, lateribus arcuato. 



Fronte arcuata, medio sinuata. 



Hab. Maria orientalia. 



Octypode (Chasmagnathus) convexa, De Haan, F. 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. GRAPSIDiE. 



The Sesarmm 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 plicatus 

 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 carina transversa valde distincta ; margine latero-anteriore 

 dentibus tribus ; parte iatero-posteriore obliqua, parte posteriore recta. 

 Chelis parvis. 

 Pedibus posterioribus perlongis, tarso vix dilatato subelongato, pilis fimbriato. 



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. 



