274 MOLLUSCA FROM THE CRAG. 
vary in form or magnitude like those so conspicuously shown in some of the 
Tellens. 
The species are not very numerous, even when admitting those which constantly 
inhabit fresh water. They are found sometimes in mud, but more frequently on sandy 
bottoms, and have a considerable vertical range. Fossil species have been found as 
early as the Lower Oolite. 
1 Corsuta striata, Walker and Boys. Tab. XXX, fig. 3, a—d. 
CARDIUM STRIATUM APICIBUS REFLEXIS. Walk. and Boys. Test. Min. Rar., p. 24, t. 3, 
fig. 85, 1787. 
TELLINA GIBBA. Olivi. Zool. Adriat., p. 101, 1792. 
— — Broce. Conch. Foss. Subap., p. 517, No. 15, 1814. 
Mya rnmquivatyis. Mont. Test. Brit., p. 38, t. 26, fig. 7, 1803. 
CorBuLA GIBBA. Nyst. Coq. Foss. de Belg., p. 65, pl. 3, fig. 3, 1844. 
= — Lovén. Ind. Moll. Scand., p. 49, 1846. 
— wucievs. Lamk. Hist. des An. s. Vert., v, p. 496, 1818. 
— —- Forbes. Report on Agean Invert., p. 180, 1845. 
= — Phil. En. Moll. Sie., vol. ii, p. 12, 1844. 
— — Bronn. Leth. Geogn., p. 967, t. 37, fig. 7, a—e. 1838. 
— striata. Flem. Brit. An., p. 425, 1828. 
— — Desh. Exped. Scient. Alger., p. 231. 
—  Rotunpata. J. Sow. Main. Conch., t. 572, fig. 4, 1827. 
= — Goldf. Petr. Germ.,, vol. ii, p. 252, pl. 152, fig. 3, a—e, 1842. 
—  Onrmperica. Costa. Cat. Syst. e. reg. Test delle 2 Sicil., p. 27, 1829. 
— tInmquivatyvis. Macgill. Moll. Aberd., p. 303, 1843. 
—  evecans. WNyst. Rech. Coq. Foss. Prov. d’Anv., p. 3, 1835. 
—  srcostata. Id. Rech. Coq. Foss. Prov. d’Any., No. 10, pl. 1, fig. 10. 
—  puanutata. Id. Coq. Foss. de Belg., p. 68, pl. 2, fig. 4, 1844. 
Not CorBuLa stRIATA. Lamk. 
Spec. Char. Testa subtriangulari, gibbosa, subinequilaterali, valde inequivalvi, valva 
dextrdé tumidiori, concentricé striatd; valvd sinistrd complanatd, sublevigatd; antice 
rotundatd, postice truncata. 
Shell subtriangular, gibbous, slightly inzequilateral, greatly inequivalve, right valve 
the more inflated, and roughly striated; left valve nearly flat and smooth; anterior 
side rounded, posterior truncated. 
Diameter, % inch. 
Locality. Coralline Crag, Sutton, Gedgrave, Ramsholt. 
Red Crag, Sutton, Bawdsey, Walton Naze. 
Recent, Scandinavia, Britain, and Mediterranean. 
In the Coralline Crag at Sutton this is one of the most common shells, and 
although furnished with an apparatus for the firm interlocking of the valves, the two 
