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, Linn(Piis. Tab. XIX, fig. 1 «— /. 



Vexcs casika. Linn. Syst. Nat., 12 id., p. IKU), No. 117, 176". 



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

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



— — lA}v/-n. Ind. Moll. Scand., p. 39, 1846. 



— DisoiN'A. Latii. An. sans Vert., t. v, p. 586, 1818. 



— KEFLEXA. Mont. Test. Brit. Suppl., pp. 41, 168, 1808. 



— RusTEBCCii. Paijr. ■Cat. Moll. Cors., p. 52, pi. i, figs. 26 — 28, 1826. 



— GiBBOSA. J. Sow. Min. Conch., t. 155, fig. 3, 1817. 



— TUEGiDA. J. Soirerhij. Min. Conch., t. 256, 1820. 



— — Nijst. Conch. Foss. de Belg., p. 178, pi. .xiii, fig. 4 a, h, 1844. 



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



— SULCATA. Nijst. Loc. cit. sup., p. 177, pi. xii, fig. 6 a, h, 1844. 



— MULTILAMELLOSA? Nyst. Id., p. 17!*, pi. xii, fig. 7 a, h. 



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



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



— CASINULA? Desh. Expi'd. Morfee, p. 101, t. xviii, figs. 18, 19. 



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

 Pectunculus membkaxacevs. Ducosta. Brit. Conch., pi. xiii, fig. 4. 



Cytuerea sulcata. Nyst et West. Nouv. Rech. des Foss. d'.Viiv., pi. i, fig. 9, 1839. 



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



Clacsixa keflkxa. Brown. Illust. Brit. Conch., pi. xix, fig. 13, 1827. 



— casina „ „ „ pi. XX, fig. 15. 

 DosiXA casixa. Gratj, Analyst, 1838. 



— TUiuuDA. iS. Wood. Catalogue. 



Spec. Char. Testa cordato-rotundaid, gihhom, inferdi/m compres-m, cra-^sd ; imhricatd 

 rel himcHafd ; lanieUihus coiiferfis, acidh ; mar/jine crenulafo ; hnudd dhlindd, impressd. 



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

 with concentric imbrications, close, sliarj), and reflexed ; margin crenulated ; lunule 

 distinct, impressed. 



Dinmder. 2 inches, nearly. 



LocaJifies. Cor. Crag, Ramsholt, Sutton, Gedgrave, Sndl)()uni. 

 Red Crag, Sutton, Bawdscy, Felixstow, Aldcrton. 

 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 individual* there is considerable 

 tumidity, while others are much compressed. 



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



