2gg CRUSTACEA. 



Again, the hexagonal Lvpas have the second, third, and fourth legs 

 very slender; moreover, the short and large eyes, which are not con- 

 cealed when retracted, give the crab a staring look. These charac- 

 ters, in connexion with the narrow form, and the transverse front 

 making an angle with the sides, show that they are a distinct group, 

 and belong together, although varying so widely in the outer maxil- 

 lipeds, as mentioned on page 74. As in the genus Lupa, these species 

 may have either a short or a long lateral tooth or spine, this distinc- 

 tion not being of generic importance. 



But Oceanus is hardly distinct from Charybdis, and Charybdis 

 graduates into Thalamita. 



The peculiar character of the Lilpa cribraria, mentioned on page 

 62, requires for it a distinct genus and family. 



The Platyonychidaa are distinct from the Portunicla?, not only in the 

 absence of the ridge on the pnclabial plate, but also in the absence 

 of the inner lobe to the inner branch of the first maxillipeds; and 

 besides, the first joint of the outer antenna? is moveable and subcylin- 

 drical like the following joint. 



The genera of Portunida? which appear to stand on good characters 

 are the following. We have doubt as to its being well to separate 

 Charybdis and Thalamita, as the transitions closely unite them, and 

 their characters are essentially the same. 



1. LUPINiE. — Sutura sterni mediana tria tegmenta intersecans. 

 Palati colliculi prominentes. 



1. Pais antennee externse mobills Jiiatu orbi/fv non <>cchi*<t, in OfMtvL jacendo aptata. 



Gr. 1. Scylla, De ITaan* — Valdo latus et cfassus, marginibus anterioribus simul 

 sumtis bene arcuatis, antero-laterali longiore quam pnstero-latcralis. Pedes 

 antici breviores, crassisshni, maim vakle tuinida, non angulata nee prismatic;!. 



Gr. 2. Lupa, Leach.-\ — Valde latus, marginibus auterioribus totis simul sumtis 

 bene arcuatis. Manus elongate trigona aut prismatica, costata. 



Or. 3. Amphitrite, De Haan,l Dana. — Angustior. Margines frontalis antero- 



* Faun. Japon., 11. 



f Ncptunus, Pontus, and Arfielous of De Ilnan (Faun. Japon., 8, 9), the distinctions 

 between which genera appear not to be sustained. 



% Faun. Japon., 8. Includes, as here adopted, the Lupa of T>e TTaan, which division 

 he restricts to the Lupaforteps (Edw. Crust., i. 456). The Litporyvtm of Adams and 

 White (Crust. Voy. Samarang, 40, pi. 12, f. 4), appears to be identical with Amphi- 

 trite. 



