OCR Text |
Show 1890.] MARINE MOLLUSCA OF ST. HELENA. 313 II. PELECYPODA. SAXICAVA ARCTICA (Linn.). Hab. Cosmopolitan. KELLIA CRASSIUSCULA. (Plate XXIV. fig. 23.) Testa globosa, rotunde ovata, nitida, alba, apices versus subpellucida, concentrice subrugose striata, fere cequilateralis ; latus anticum posteriore paulo angustius; pagina interna cdba, incrassata, minute subrugosa ; linea cardinalis crassiuscula, clente vel tuber-culo cardinali et laterali posteriore tuberculari in utraque instructa ; ligamentum internum pone umbones situm. Longit. 6|- millim., alt. 5, diam. 3|. For a shell of such small size it is rather thick. The umbones are only very slightly elevated, curved towards the anterior end, and capped at the tip with a minute embryonic shell. KELLIA ATLANTICA. (Plate XXIV. fig. 24.) Testa minuta, oblongo-rotundata, incequilateralis, sordide albida, concentrice tenuissime striata ; margo dorsi anticus valde declivis, leviter convexus, posticus longior, subhorizontalis ; latus anticum acute rotundatum, posticum latius excurvatum ; margo inferior late arcuatus. Dens cardinalis valvce sinistra? fcformce, valvce dextrce unicus prominens, acutus; dens lateralis posticus in utraque valva elongatus, in clextra validus, margine dorsali sidco separatus. Longit. 2| millim., alt. 2, diam. 1^. This species is about the size of Lepton clarkia, but not of the same form. MONTACUTA SUBTRIANGULAR1S, (Plate XXIV. fig. 25.) Testa fere cequilateralis, mediocriter convexa, sordide albida, nitida, rotunde subtrianguluris, lineis incrementi striata, postice quam antice paulo angustior ; margo dorsalis utrinque declivis, postice vix excurvatus, antice leviter concavus, ventralis rectus in medio levissi7ne incurvatus; umbones prominuli, subacuti; pagina interna nitida, prope margine incrassata; cicatrices macjnce, subpyriformes; denies duo valvce sinistral prominentes, divergentes. Longit. 4 | millim., alt. 3g, diam. 2g. This species has the dorsal margin sloping on each side and the base almost straight, so that a somewhat triangular shape is produced, the two lower angles being well rounded. LUCINA (CODAKIA) IMBRICATULA, C. B. Adams. Lucina imbricatula, C. B. Adams, Proc. Boston Soc. Nat. Hist. 1845, vol. ii. p. 10 ; id. Contrib. Conch, p. 245. |