231 



color, and sculpture, excepting that we here have punctures instead 

 of granules. It is closely allied to if not a variety of C. lignosus. 



Crania [Discina] radiosa. T. suborbicularis, inequivalvis, cras- 

 siuscula, citrina, costulis radiantibus divaricantibus, et striis concen- 

 tricis cancellata ; valva superiori convexti, apice acuto, post-mediano ; 

 valva inferiori planulata, concentrice laminos;i et interdum versus 

 peripheriam radiatini eostulata, fissura minima perforata : intus crista 

 acuta iu valva inferiori apophysin furcatum gerente, bipartita ; cica- 

 tricials incrassatis ; marginibus ciliatis. Diam. 1 ; lat. \ poll. 



One specimen found at Rio Janeiro, which seems to be identical 

 with specimens from Cape Palmas, and from which the description is 

 mainly drawn. 



Argonauta geniculata. Corpus ovatum, supra gibbosum ; 

 caput breve, angustum : oculi magni, prominentes, pupillo nigro, 

 iride aurato : sipho conicus, elongatus : os magnum ; rostris fortibus : 

 brachia basi adnata, superioribus cylindraceis, geniculatis, vexillum 

 semiellipticmn, llocculosum gerentibus ; brachiis secundis longissimis : 

 color virescenti-argentata, punctis chocolatis oculatis variegata. 

 Whole length, 6 inches ; breadth, l£ in. ; length of sac 2£ in.; length 

 of superior arms, 5 in. ; inferior, 4^ in. ; superior lateral, 6 in. ; in- 

 ferior, 4 ; diam. of umbrella, \\ inches. Taken near the Sugarloaf, 

 Rio Janeiro. Couthouy. 



Resembles most nearly A. arrjo. The joint-like flexure of the arms 

 is different from that of any described species. 



Octopus megalocyathus. Corpus ovatum, laeve, chocolatum 

 lineis cinereis marmoratum, membrana laterali angusta quasi natatoria 

 munitum: caput angustum : oculi prominuli : siphon bulbosus, curtus : 

 os magnum, rostris nigris : umbella amplissima : brachia longissima ; 

 acetabulis confertis, maximis. Length of head to eyes, 2.7; of body, 

 7.5 ; of arms, 34 ; circumference of body, 11 ; of arms, 3 ; breadth 

 of umbrella, 8 : of largest cupule, 1.3 inches. Orange Harbor. 

 Lieut. Alden. 



Remarkable for the size of its umbrella and cupules, and especially 

 for the narrow membrane along the sides of the body, which has 

 been noticed in no other species except 0. membranaceus Quoy. It 

 is closely allied to O. Fontainianus D'Orb. ; 0. tehuelca comes from 

 the same region and has the same general characters. [Allied to 

 Pinnoctopus D'Orb.] 



Octopus mimus. Corpus parvum, ovato-globosum : caput angus- 

 tum : oculi parvi, exstantes ; papillo nigro ; iride aurato et miuiato : 

 apertura ad angulos maculis rufis flavo-cinctis oculos simulantibus 

 signata : brachia robusta, corpore quater excedentia pro longitudine 

 3, 2, 4, 1 ; acetabulis remotis, purpureo cinctis : umbella amplissima : 



