1852.] 73 



Conspectus Crustaceorum, 6'c. Conspectus of the Crustacea of the Exploring 

 Expedition under Capt. Wilkes, U. S. N.. including the Crustacea Can- 

 cRoiDEA Corystoidea. By James D. Dana. 



I. CRUSTACEA CANCROIDEA. 



A synopsis of the genera of Cancroidea the Cyclometopa of Edwards in-, 

 eluding their arrangement into families and other groups, has been published by the 

 writer in the American Journal of Science, 2d ser., vol. xii, p. 121. The follow- 

 ing pages contain descriptions of the new species in the Expedition collections, 

 arranged in accordance with the classification explained in that paper. The 

 distinctive characters of the genera will there be found, both of those of other 

 authors, as far as accepted, and those here instituted. 



Fam. I. CANCRIDaE. 

 Subfam. CANCRIN.E. 



Genus Cancer, Leach, (Platycarcinus, Udw.) 



Cancer magister. Carapax nudus, granulatus, paulo convexus, superficie 

 paulo undulatus, lateraliter triangulatus et acutus, margine postero-laterali fere 

 recto, antero-laterali lO-dentato, dentibus paululo prominentibus, margine 

 dentis postero longissimo et fere recto, subtiliter crenulato, dente ultimo 

 triangulato ; fronte inter-antennali 3-dentato ; articulo antennarum externarum 

 Imo apicem crasse producto. Pedes antici subaequi, manu supra cristata, multi- 

 dentata, extus costata, digito mobili supra denticulato. Pedes 8 postici valde 

 compressi, tarso paulo lato, articulis supra granulatis, 4to supra canaliculato, 

 tarso articuloque 5to pedis 5ti infra bene ciliatis. Articulus maxillipedis externi 

 3tius oblongus, apice externo oblique truncatus. Hai^. portu " San Francisco." 

 Long, carapacis 4|", /at. 1". 



^ Cancer gracilis. Carapax nudus, partim minute granulatus, valde convexus, 

 non distincte areolatus, superficie non undulatus, lateraliter triangulatus et 

 acutus, margine postero-laterali fere recto, antero-laterali 9-dentato, dentibus 

 regularibus, acutis, paulo prominentibus, dente Imo vix longiore quam 2dus, 

 totis margine postero fere rectis et longis et subtiliter denticulatis, fronte inter- 

 antennali 3-dentato. Maxillipedes externi pubescentes, articulo 3tio apicem 

 externum valde arcuato aut rotundato, margines apicalem et externum longe 

 ciliato. Pedes antici subaequi, manu subcristata, crista 1 2-dentata, superficie 

 externa costata. -Pedes 8 pastici nudi, tarso longo, tenuissimo, nudo. Hab. 

 portu " San Francisco." Long, carapacis 13'", lat. 19'". 



Subfam. XANTHIN.^. 

 Genus Liomera, Dana. 



Carpilio, aspectu, pedibus nudis quoad margines obtusis antennisque similis. 

 Carapax valde transversus, subellipticus, lateribus rotundatis, margine antero- 

 laterali non breviore quam postero-lateralis, fronte brevissime bilobato. Ramus 

 maxillipedis primi internus non lobatus, apice fere rectus. Pedes usque ad 

 tarsos nudi. An Carpilius cinctivianusy White, hie pertinet ? 



LioMERA LATA. Carapax nitidus, valde transversus, transversim bene 

 ellipticus, antice versus marginem anticum subareolatus, in medio areolis in- 

 conspicuis ; fronte brevi, perpendicnlariter deflexo, superne viso fere recto et 

 super orbitas vix saliente, leviter emarginato ; margine antero-laterali crasso et 

 crasse rotundato, 4-lobato, lobis 2do 3tio 4toque validis, rotundatis, 3tio majore. 

 Pedes antici asqui, mediocres, manu laevi, digitis brevibus. Hah. ad insulas 

 *'Feejee." Iro??o-. carapacis 7'", lat.\'i\"'. 



Genus Act^a, [DeHaan) Dana. 



AcT^A AREOLATA. A. hirtissimo vel specioso aflfiinis. Carapax latior, valde 

 transversus, infra omnino brevissime hirsutus, supra omnino areolatus, sub- 



