BIVALVIA. 165 
America; though not numerous in species, they are widely distributed. They 
are all marine, and probably, from the thickness of their shells, were inhabitants 
of not very deep water. The animal is said to be occasionally fixed by a byssus, 
though that is seldom the case, as, generally, the valves are capable of being 
perfectly closed. 
It does not appear to be a very ancient genus, though largely developed in the 
Tertiaries. 
1. CaRpITa sENtLIS, Lamarck. Tab. XV, fig. 1 a—y. 
VENERICARDIA SENILIS. Lam. Ann. du Mus., t. vii, p. 57. 
— — Id. Hist. des Eny. de Par., p. 222. 
= — Desh. 2d ed. Lam., Hist. des An. s. Vert., t. vi, p. 384, 1835. 
— —_ Parkinson. Org. Rem., vol. iii, p. 191, pl. xiii, figs. 15, 17, 1811. 
_ a J. Sow. Min. Conch., t. 258, figs. 1—3, 1820. 
— —_ Nyst. Rech. Coq. Foss. d’Anv., p. 11, No. 43, 1835. 
— — Lyell. Trans. Geol. Soc., 2d ser., vol. v, p. 245, fig. 1, 1836. 
— ANTIQUATA. Leathes’ MS., fide J: Sowerby. 
_ INTERMEDIA? Dubois. Wolh. Podol., p. 61, pl. v. figs. 20-1, 1831. 
CarpiTa sauamuLosa. Wyst. Coq. Foss. de Belg., p. 207, pl. xvi, fig. 4 6, and fig. 5 a, 6, 
1844. 
Dale. Hist. and Antiq. of Harw., p. 291, t. xn, fig. 4, 1730. 
Spec. Char. Testa obliquée-cordata, inequilaterah, oblonga, sub-quadratd vel orbiculari ; 
compressa vel turgidd, crassa, clausa ; costis 17—20 magnis, convewis, rugosis, interdim 
squamis, elevatis, fornicatis, asperis; lunuld parva, impressd, dentibus crassis, perpendicu- 
lariter striatis. 
Shell obliquely heartshaped, inequilateral, oblong, subquadrate, or orbicular, 
tumid or compressed, thick, strong, and closed, furnished with 17—20 large, convex, 
rugose coste, sometimes ornamented with distant, arched, and elevated squame; 
lunule small, deeply impressed, teeth thick, and striated in a vertical direction. 
Largest Diameter, \% inches. 
Localities. Cor. Crag, Ramsholt, Sutton, Sudbourne, and Gedgrave. 
Red Crag, Sutton, Newbourn, Alderton, Bawdsey, Felixstow. 
At Gedgrave it may be procured by hundreds, and occasionally with the valves 
united, when it forms one of our handsomest shells. It appears to have flourished in 
great profusion during the period of the Coralline Crag; and from the large number of 
specimens met with in the Red Crag, it may probably have extended its existence into 
the period of that deposit, although I have not yet found it at Walton-on-the-Naze.* 
This is also one of the most variable of the whole class of Bivalves. The shell 
with this name, as given from the Environs of Paris by Lamarck, is probably an error, 
at least I have not been able to see an Eocene species with which it could be identified ; 
* Dale gives it from Harwich, but as a shell of rare occurrence. 
