BIVALVIA. 153 
this species has been very rarely met with, it may possibly have been more abundant in 
that part of the Crag whence his shells were taken, but now long since washed 
into the sea. 
C. echinatum, Dubois, ‘ Wolhyn. Pod.,’ pl. vi, figs. 13, 14, does not appear from the 
figure to correspond with our shell. 
2. CarpiuM Noposum, Montague. Tab. XIII, fig. 4a—c. 
CarpiumM Noposum. Mont. Test. Brit., p. 81, 1803. 
— — Turt. Brit. Biv., p. 186, t. xiii, fig. 8, 1822. 
— — Hanley. Recent Shells. Supp., pl. xvii, fig. 44. 
— — Reeve. Conch. Icon. Cardium, pl. xxii, fig. 128. 
— — Lovén. Ind. Moll. Scandia, p. 36. 
— — Alder. Catal. Moll. North. and Durh., p. 83, 1848. 
— — Forbes and Hanl. Hist. Brit. Moll., vol. ii, p. 22, pl. xxxii, fig. 7, 1849. 
— DISCREPANS? Brown. Illust. Brit. Conch., pl. xxii, fig. 9, 1827. 
— scaBrum. Phil. En. Moll. Sic., vol. ii, p. 38, vol. xiv, p. 16, 1844. 
— — Hanley. Rec. Shells. Supp., pl. xvii, fig. 43. 
Spec. Char. Testd parvd, ovato-orbiculari, parum converd, sub-equilaterali, antice 
rotundatd, postice truncata ; costis circa 26 planulatis, nodulosis ; interstitirs punctatis. 
Shell small, somewhat orbicular, slightly convex, a little inequilateral, anterior side 
rounded, posterior truncated ; ribs about 26, flattened, and ornamented with tubercles ; 
interstices narrow and punctated. 
Length, 4 an inch nearly ; height, 3ths do. 
Locality. Cor. Crag, Sutton. 
Red Crag, Sutton, Alderton, Bawdsey. 
Recent, Mediterranean, Britain, Scandinavia. 
This species is particularly abundant, more especially in the Coralline Crag, at Sutton, 
where the larger specimens are generally much altered by the loss of all the outer 
coating of the shell, and with it, of course, its tubercles; but in the younger state it 
may be obtained plentifully in high perfection, and in some specimens the tubercles are 
very deciduous, while in others they cover the entire surface. The diameter is in general 
greater from the anterior to the posterior side, than from the umbo to the ventral 
margin: it is not so inall. It may be very well distinguished by its contour, which is 
slightly angular on the hinder side, but less so than in C. exiguum. The ribs are very 
flat and broad, and the interspaces so narrow, that it is only occasionally the ridges or 
punctated surface of those furrows can be seen. On the anterior and central portion 
of the shell, the nodules, when remaining, are broad and obtuse, reaching across the 
ribs, while on the posterior side, the ribs are more convex, and only ornamented in the 
centre with sharper or smaller tubercles. 
