274 MOLLUSCA FROM THE CRAG. 



vary in form or magnitude like those so conspicuously shown in some of the 



Tettens. 



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. CORBULA STRIATA, Walker and Soys. 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. 



Broc. Conch. Foss. Subap., p. 517, No. 15, 1814. 

 MYA IN/EQUIVALVIS. Mont. Test. Brit., p. 38, t. 26, fig. 7, 1803, 

 CORBULA GTBBA. Nyst. Coq. Foss. de Belg., p. 65, pi. 3, fig. 3, 1844. 



Loven. Ind. Moll. Scand., p, 49, 1846. 



NUCLEUS. Lamk. Hist, des An. s. Vert., v, p. 496, 1818. 



Forbes. Report on jEgean Invert., p. 180, 1843. 



Phil. En. Moll. Sic., vol. ii, p. 12, 1844. 



Bronn. Leth. Geogn., p. 967, t. 37, fig. 7, a c. 1838. 



STRIATA. Flem. Brit. An., p. 425, 1828. 



Desk. Exped. Scient. Alger., p. 231. 

 ROTUNDATA. J. Sow. Min. Conch., t. 572, fig. 4, 1827. 



Goldf. Petr. Germ., vol. ii, p. 252, pi. 152, fig. 3, a e, 1842. 



OLIMPLTCA. Costa. Cat. Syst. e. reg. Test delle 2 Sicil., p. 27, 1829. 



IN^QUIVALVIS. Macgill. Moll. Aberd., p. 303, 1843. 



ELEGANS. Nyst. Rech. Coq. Foss. Prov. d'Anv., p. 3, 1835. 



BICOSTATA. Id. Rech. Coq. Foss. Prov. d'Anv., No. 10, pi. 1, fig. 10. 



PLANULATA. Id. Coq. Foss. de Belg., p. 68, pi. 2, fig. 4, 1844. 

 Not CORBULA STRIATA. Lamk. 



Spec. Char. Testa subtriangulari, gibbosd, subin&quilaterali, valde inceguivalvi, valvd 

 dextrd tumidiori, concentrice striatd; valvd sinistrd complanatd, sublcevigatd ; antice 

 rotundatd, postice truncatd. 



Shell sub triangular, gibbous, slightly insequilateral, 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, Button, 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 



