196 MOLLUSCA FROM THE CRAG. 
1. Cyprina Istanpica. Linn. Tab. XVIII, fig. 2 a—d. 
ProruncuLus Maximus. List. Hist. Conch., fig. 108, 1685. 
— _ Dacosta. Brit. Conch., p. 183, t. xiv, fig. 5, 1778. 
Venus Isuanpica. Linn. Syst. Nat., ed. 12, p. 1131, No. 124, 1767. 
= — Mill. Zool. Dan., vol. i, p. 29, pl. xxviii, figs. 1—5, 1776. 
— Icrranpica. W. Wood. Ind. Test., pl. vii, fig. 4], 1825. 
— MERCENARIA. Penn. Brit. Zool., ed. iv, vol. iv, p. 94, pl. lit, fig. 47. 
— sucarpium. Born. Mus. Ces. Vind., t. iv, fig. 11, 1780. 
— kEaqualis. J. Sow. Min. Conch., t. xxi, 1813. 
Cyprtna Istanpica. LEncy. Meth., pl. 301, fig. 1 a, 6, 1789. 
— — Phil. En. Moll. Sie., vol. ii, p. 31, 1844. 
— — Nyst. Conch. Foss. de Belg., p. 146, pl. ix, fig. 1, and pl. ii, fig. 1, 
1844. 
— — Agass. Icon. des Coq. Tert., p. 49, t. xiii, figs. 6, 7, 1845. 
— — Dekay. Nat. Hist. New York Zool., pl. xxvi, figs. 268-9, 1843. 
— — Lovén. Ind. Moll. Seand., p. 38, 1846. 
—  Istanptcorpes. WNyst. Coq. Foss. Prov. d’Anv., p. 9, No. 33, 1835. 
— —- Pusch. Pol. Pal., p. 74, pl. vin, fig. 5 a—e, 1837. 
— aneutata. Myst. Rech. Coq. Foss. d’Anv., p. 9, No. 34, 1835. 
— maxima. S. Wood. Catalogue, 1840. 
— vuiearis. G. B. Sow. Genera of Shells, No. 32, 1824. 
— mavuatis. Phil. En. Moll. Sic., vol. i, p. 39, t. iv, fig. 4, 1836. 
— — Goldf. Pet. Germ., p. 236, pl. 148, fig. 5, a, b. 
— — Agass. Icon. des Coq. Tert., p. 52, t. xiii, fig. 5, 1845. 
ARCTICA VULGARIS. Schum. Essai d’un Nouv. Syst. des Habit. des Vers. Test., p. 145, 
pl. xin, fig. 3, 1817. 
Spec. Char. Testdé magnd, subcordatd, transversd, vel orbiculari, tumidiusculd; stris 
aut lineis incrementi tenuibus et irregularibus ; umbonibus acutis vie incurvatis ; latere 
postico subangulato. 
Shell large, of a subcordate form, sometimes elongate or transverse, at others 
nearly orbicular, somewhat tumid, covered with fine and irregular lines of growth ; 
beaks sharp, not prominent, scarcely incurved, posterior side slightly angulated. 
Diameter, 45 inches. 
Localities. Cor. Crag, Gedgrave, Ramsholt. 
Red Crag, Sutton, Bawdsey, Alderton, Felixstow. 
Mam. Crag, Bridlington, Southwold, Chillesford. 
Uddevalla and Clyde Beds. 
Recent, British, Norwegian, and North American Seas. 
This is one of the most common and abundant shells of the Coralline Crag, and 
although perfect specimens are somewhat difficult to obtain in the disturbed portion 
of the Red Crag, fragments or imperfect specimens are there of no uncommon occur- 
rence, neither is it very rare in the still more recent deposit of the Mammaliferous 
Crag. It is found living upon our own coasts in various depths of water from five to 
thirty fathoms, and mostly where the bottom is of sandy mud, but it is considered as 
