CANCROIDEA. 269 



lateralisque angulo convenientes, antero-laterali raro breviore quam postero-late- 

 ralis. Manus elongata, prismatica. Basis antennae externae crassus, hiatu orbitae 

 parce angustior. 

 Gr. 4. Carupa, Dana. — Transversus. Margines frontalis antero-lateralisque an- 

 gulo convenientes, fronte recto, medio ssepe emarginato. Basis antennas externae 

 subcylindricus, hiatu orbitae multo angustior. 



2. Pars ant.ennarum extemarum mob ills hiatu orbitae, omnino per basis jprocessum 

 occlusa, orbitdplus minusve remota. 



Gr. 5. Thalamita, Latr. — Latus. Frons dimidio latitudinis carapacis longior ; 

 margo antero-lateralis longitudinalis. Articulus antennae externae lmus prae- 

 longus, 2dus orbita, remotissimus. Pedes antici longi, manu elongate. 



Gr. 6. Charybdis, Be Haan, Dana* — Angustior. Frons dimidio latitudinis cara- 

 pacis brevior; margo antero-lateralis obliquus. Articulus antennae externae lmus 

 paulo oblongus, 2dus orbitsi, paulo remotus. Pedes antici longi, manu elongate. 



Gr. 7. Lissocaroinus, White.^ — Suborbiculatus, lsevis, subporcellanus. Articulus 

 antennae externae lmus brevis, fere longitudinalis, articulo sequente orbita parce 

 remoto. Pedes nudi; antici breves, brachio ultra carapacem vix saliente, manu 

 perbrevi. 



2. ARENiEINiE. — Sutura sterni mediana tria segmenta intersecans. 

 Palatum colliculo utrinque non di visum. Ramus maxillipedis lmi 

 internus ad apicem late transversim triangularis, duobus inter se 

 fere convenientibus. 



Gr. Aren^eus, Dana. — Lupse aflinis. Carapax valde latus, antice arcuatus. Pars 

 antennae externae mobilis hiatu orbitae insita. Manus prismatica. 



3. PORTUNINiE. — Sutura sterni mediana duo segmenta intersecans. 

 Colliculi palati ssepe obsoleti. 



(x. Portdnus, Fabr. — Angustus, margine antero-laterali breviore quam postero- 

 lateralis.J 



* Fauna Japon., 10. Includes both Charybdis and Oceanus of De Haan. Corre- 

 sponds to the " Thalamites Hexagonales" of Edwards, Crust., i. 461. 



-j- Crust. Voy. Samarang, 45. We have taken the generic characters from a species 

 collected by us, in connexion with the description by White. 



J The above synopsis of Portunidae, is published by the author in the Amer. J. Sci., 

 [2], xii. 129, 1851. 



68 



