CANCROIDEA. 269 



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

 ralis. Maims elongata, prismatica. Basis antennae externaa crassus, hiatu orbitae 

 parce angustior. 



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

 gulo convenientes, fronte recto, rnedio saepe emarginato. Basis antenna; externae 

 subcylindricus, hiatu orbita multo angustior. 



2. Pars antennarum externarum mabilis hiatu orbitae omnino per basis processum 

 occlusa, orbita plus minusve remota. 



G. 5. THALAMITA, Latr. Latus. Frons dimidio latitudinis carapacis longior; 

 margo antero-lateralis longitudinalis. Articulus antennas externse Imus prae- 

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



Gr. 6. CHARYBDIS, De Haan, Dana* Angustior. Frons dimidio latitudinis cara- 

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

 paulo oblongus, 2dus orbita, paulo remotus. Pedes antici longi, manu elongatS.. 



Gr. 7. LISSOCARCINUS, White. ^ Suborbiculatus, laevis, subporcellanus. Articulus 

 antennae externse Imus brevis, fere longitudinalis, articulo sequente orbita parce 

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

 perbrevi. 



2. AREN^EIN^E. Sutura sterni mediana tria segmenta intersecans. 

 Palatum colliculo utrinque non divisum. Ramus maxillipedis lini 

 internus ad apicem late transversim triangulatus, duobus inter se 

 fere convenientibus. 



G. AREN^EUS, Dana. Litpse affinis. Carapax valde latus, antice arcuatus. Pars 

 antennae externae mobilis hiatu orbitae insita. Manus prismatica. 



3. PORTUNINJ3. Sutura sterni mediana duo segmenta intersecans. 

 Colliculi palati saepe obsoleti. 



G. PORTUNUS, Fabr. Augustus, margine antero-laterali breviore quam postero- 

 lateralis.J 



* Fauna Japon., 10. Includes both Cliarybdis 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. 



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

 [2], xii. 129, 1851. 



68 



