BIVALVTA. 275 



pieces are not often found in their natural position. In the Red Crag even the 

 separated valves are by no means abundant. 



Cardium striatum, of Walker and Boys, is evidently the same as our shell, and Dr. 

 Fleming adopted that name as most entitled to priority : I followed his example in my 

 Catalogue, and see no reason why it should now be changed. In the fossil state, this 

 species is liable to great alteration : the outer coating which forms a perfect shell of 

 itself, with its thick transverse ridges, comes off, leaving the inner portion perfectly 

 smooth. Corbula planulata, in Sir Charles Lyell's Cabinet, received from Belgium, with 

 that name, is, I believe, only this species in its exfoliated or decorticated condition. 



Sir Charles Lyell, in his paper upon the ' Miocene Deposits of America/ has 

 considered Corbula elevata, of Conrad, the same as this species, and judging from the 

 figure by that author, he is probably correct in that assignment. 



A single valve, of which I have given a representation (fig. 4), may probably be 

 C. rosea, but in such a genus as this, in which the species are by no means easily 

 defined, I prefer leaving it without description for the present. 



2. Corbula complanata, /. Sowerby. Tab. XXX, fig. 2, a — d. 



Corbula complanata. J. Sow. Min. Conch., t. 302, figs. 7, 8, 1822. 



— - Desk. Coq. Foss. des Env. de Par., pi. 7, figs. 8, 9, 1824. 



— — Dujard. Mem. de la Soc. de France, torn, ii, pt. 2, p. 256, 1837. 



— — Desk. 2d ed. LamJc. torn, vi, p. 142, 1835. 



— — Grat. Cat. Zool. des An. du Basin Tert. de la Gironde, p. 67, 



No. 794, fig. 3, 1838. 



— — Bronn. Leth. Geogr., p. 969, t. 37, fig. 8, a, b, 1838. 



— donaciformis. Nyst. Reck. Coq. Foss. de Hoesselt et Kl. Spawen, p. 3, No. 6, 



pi. 1, fig. 6, 1836. 

 Corbulomya complanata. Nyst. Coq. Foss. de Belg., p. 59, pi. 2, fig. 2, 1844. 

 Erycina trigona. Lamk. Ann. du Mus., torn, vi, p. 413, No. 3. 



Spec. Char. Testa transversa, ovatd, vel donaciformi incequilaterali, compressd aut 

 complanata, lavigatd, crassd ; antice majiore rotundatd; postice angulatd, truncatd, et sub- 

 carinatd ; dente cardinali unico in valvd dextrd. 



Shell transverse, ovate, or wedge-shaped, inequilateral, compressed or flattened, 

 smooth, and thick ; anterior side the larger and rounded ; posterior angulated, 

 truncated, and slightly keeled ; one cardinal tooth in the right valve. 



Length, \\ inch. Height, § inch. 



Locality. Red Crag, Sutton and Walton Naze. 



Fossil in the Paris basin, and at Kleyn Spauwen, the Basin of the 

 Gironde, and in the Faluns of Touraine. 



This is a rare shell, though solid and strong, and does not appear to have been an 

 inhabitant of the Coralline Crag sea, though a species supposed to have been trans- 



