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, Linnaus. Tab. XIX, fig. 1 «— /. 



Venus casina. lAnn. Syst. Nat., 12 ed., p. 1130, No. 117, 1767. 



— — Bujard. Mem. de la Soc. Geol. de Fr., t. ii, part 2, p. 261, 1837. 

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



_ _ Lovin. 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. 26—28, 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 a, b, 1844. 



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



— SULCATA. Nyst. Loo. 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. Morfee, p. 101, t. xviii, figs. 18, 19. 



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

 Pectunculus membranaceus. 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. Browu. Illust. Brit. Conch., pi. xix, fig. 13, 1827. 



— casina „ „ „ pi. XX, fig. 15. 

 DosiNA casina. Cfray, Analyst, 1838. 



— TURGTDA. S. Wood. Catalogue. 



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

 V el lamellata ; lamellibus conferfis, acutis ; margine crenulato ; lunula 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, Sudboum. 

 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 



