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Show 1890.] MARINE M O L L U S C A O F ST. H E L E N A . 303 'Challenger' Lamellibranchiata, p. 161. It has not previously been met with so far south in the eastern parts of the Atlantic. ROCELLARIA DUBIA (Pennant). Hab. Mediterranean, Red Sea, North Sea, Madeira, Canary Islands, Cape Verde Islands. St. Helena is, I believe, the most southern locality known for this species. CHAMA, sp. Several specimens of a species of this genus were collected by Capt. Turton. The young examples exhibit short spines on both valves, but the adult shells are too worn to be determined. The interior is white, more or less stained with brown, especially towards the margins. Length of largest specimen 75 millim. C. gryphoides, Linn., appears in Jeffreys's and Melliss's lists of St. Helena shells. I have not seen the specimens which they examined, but doubtless they belonged to the same species as those collected by Capt. Turton. It is probable that they are correctly identified, but in such a difficult group as Chama one hesitates to pronounce a positive opinion without a special study. BASTEROTIA OBLONGA. (Plate XXII. figs. 5, 5 a.) Testa oblongo-subquadrata, valde ina>quiluteralis, albida, concen-trice striata ; valvce cequales, ab umbone ad extremitatem posti-cam obtuse angulatce ; margo dorsi posticus fere rectus, ventralis subrectilinearis, vel in medio leviter incurvatus; latus anticum breve, obliquum, inferne rotunclatum, posticum oblique curvalum, ad extremitatem acute rotundatum ; umbones parvi, acuti, ante-mecliani, circiter in\ longitudinis siti; dens cardinalis in utraque valva prominens, acutus ; pagina internet nitida ; cicatrices bene impressce. Longit. 8| millim., alt. 5, diam. 4\. This is a more oblong species than B. carinata or B. gouldii and some others. This group of shells was first recognized by Gray in 1842 (Synopsis Contents Brit. Mus. p. 78) and named Hctrlea. His description runs thus:-"The Hctrlea are oblong, subquadrate, thin shells, with a sharp keel from the umbo, and conical hinge-teeth." This diagnosis applies perfectly to the type marked by Gray himself as Hctrlea, and this was described the year following (1843) by Hinds as Corbula quadrata. This species also forms the type of Recluz's genus Eucharis (1850), and Homes in 1859 described a fossil species belonging to the same group under the generic name Basterotia. Considering the imperfection of Gray's description, and the fact of his not citing any species, I think it would be advisable to ignore his genus Harlea, although, personally, I am sure what group he intended to include under that name. A genus Eucharis having been published by Latreille in 1804, this name cannot be employed for the present group of shells. We 21* |