210 MOLLUSCA FROM THE CRAG. 



Fossils in the Carboniferous Deposits have been assigned to this genus, but 

 perhaps their just claim will not go further than a resemblance, or what is called a 

 family relationship, their true characters not having been well determined. 



1. VENUS CASINA, Linncsus. Tab. XIX, fig. 1 af. 



VENUS CASINA. Linn. Syst. Nat., 12 ed., p. 1130, No. 117, 1767. 



_ Dujard. Mem. de la Soc. Geol. de Fr., t. ii, part 2, p. 261, 1837. 

 Phil. En. Moll. Sic., vol. ii, p. 33, 1844. 

 Loven. Ind. Moll. Scand., p. 39, 1846. 



DISCINA. Lam. An. sans Vert., t. v, p. 586, 1818. 



REFLEXA. Mont. Test. Brit. Suppl., pp. 41, 168, 1808. 



RUSTERUCII. Payr. Cat. Moll. Cors., p. 52, pi. i, figs. 2628, 1826. 



GIBBOSA. J. Sow. Min. Conch., t. 155, fig. 3, 1817. 



TURGTDA. J. Sowerby. Min. Conch., t. 256, 1820. 



Nyst. Conch. Foss. de Belg., p. 178, pi. xiii, fig. 4, b, 1844. 



SENILIS? Dubois. Wolhyn. Podol., p. 60, pi. v, figs. 22, 23. 



SULCATA. Nyst. Loc. cit. sup., p. 177,' pi. xii, fig. 6 a, b, 1844. 



MULTILAMELLOSA ? Nyst. Id., p. 179, pi. xii, fig. 7 a, b. 



SIMILIS? Id. Id., p. 180, pi. xiii, fig. 5 a, b. 



GALLINA? Bronn. Leth. Geog., vol. ii, p. 948, t. xxxviii, fig. 6. 



CASINULA? Desk. Exped. Moree, p. 101, t. xviii, figs. 18, 19. 



CINCTA. Agass. Icon, des Coq. Tert., p. 36, t. iv, figs. 7 10, 1845. 

 PECTUNCULUS MEMBBANACETJS. Dacosta. Brit. Conch., pi. xiii, fig. 4. 



CYTHEREA SULCATA. Nyst et West. Nouv. Rech. des Foss. d'Anv., pi. i, fig. 9, 1839. 



LAMELLATA. Id. p. 9, pi. i, fig. 10. 



CLAUSINA REFLEXA. Brown. Illust. Brit. Conch., pi. xix, fig. 13, 1827. 



CASINA pi. xx, fig. 15. 



DOSINA CASINA. Gray, Analyst, 1838. 

 TURGIDA. S. Wood. Catalogue. 



Spec. Char. Testa cordato-rotundatd, gibbosd, interdum compressd, crassd ; imbricatd 

 vel lamettatd ; lamellibus confertis, acutis ; margine crenulato ; lunuld distinctd, impressd. 



Shell roundedly heartshaped, gibbous, sometimes compressed, thick, and covered 

 with concentric imbrications, close, sharp, and reflexed ; margin crenulated ; lunule 

 distinct, impressed. 



Diameter. 2 inches, nearly. 



Localities. Cor. Crag, Ramsholt, Sutton, Gedgrave, Sudbourn. 

 Red Crag, Sutton, Bawdsey, Felixstow, Alderton. 

 Mam. Crag, ? Clyde beds. 



Recent, Mediterranean, Britain, Bergen. 



This shell as a Crag fossil is everywhere abundant, and exceedingly variable in 

 outward form, being sometimes longer than it is high, while in other specimens the 

 diameter is greater in the opposite direction ; in some individuals there is considerable 

 tumidity, while others are much compressed. 



It is assigned to the living species from the belief that some of its varieties 



