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, Linneus. Tab. XIX, fig. 1 a—f. 
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. 
— — Lovén. Ind. Moll. Scand., p. 39, 1846. 
— piscina. Lam. An. sans Vert., t. v, p. 586, 1818. 
— perpexa. Mont. Test. Brit. Suppl., pp. 41, 168, 1808. 
—  Rusrervct. Payr. Cat. Moll. Cors., p. 52, pl. i, figs. 26—28, 1826. 
— ipposa. J. Sow. Min. Conch., t. 155, fig. 3, 1817. 
— uretpa. J. Sowerby. Min. Conch., t. 256, 1820. 
— — Nyst. Conch. Foss. de Belg., p. 178, pl. xiii, fig. 4, 6, 1844. 
—  senitis? Dubois. Wolhyn. Podol., p. 60, pl. v, figs. 22, 23. 
—  sutcata. Myst. Loe. cit. sup., p. 177, pl. xii, fig. 6a, b, 1844. 
— MULTILAMELLOSA? WNyst. Id., p. 179, pl. xii, fig. 7 a, 6. 
—  sIMILIs? Id. d., p. 180, pl. xiii, fig. 5 a, 6. 
— Gattina? Bronn. Leth. Geog., vol. ii, p. 948, t. xxviii, fig. 6. 
— casinuLa? Desh. Exped. Moree, p. 101, t. xviii, figs. 18, 19. 
—  crneta. Agass. Icon. des Coq. Tert., p. 36, t. iv, figs. 7—10, 1845. 
PECTUNCULUS MEMBRANACEUS. Dacosta. Brit. Conch., pl. xiii, fig. 4. 
CyrHprea sutcata. Myst et West. Nouv. Rech. des Foss. d’Anv., pl. i, fig. 9, 1839. 
— LAMELLATA. Id. S5 3 55 p. 9, pl. i, fig. 10. 
CLAUSINA REFLEXA. Brown. Illust. Brit. Conch.. pl. xix, fig. 13, 1827. 
— CASINA BA % 35 pl. xx, fig. 15. 
Dostya castna. Gray, Analyst, 1838. 
— urea. S. Wood. Catalogue. 
Spec. Char. Testé cordato-rotundatd, gibbosd, interdum compressa, crassa ; imbricata 
vel lamellatd ; 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 
