CARDIUM. 139 



It is rather smaller, more triangular, more compressed, more 

 dee})ly and regularly grooved, than G. g-emma, and destitute of pur- 

 ple within and without. 



Family CARDIAD^. 



Shell somewhat heart-shaped ; cardinal teeth two or three ; lat- 

 eral teeth one or two ; radiately ribbed or furrowed. Mantle open, 

 siphons very short, foot very large and kneed. 



Cieiiiis CARDIUl?!, Lix. - 1758. 



Shell somewhat heart-shaped ; Ijeaks prominent ; margin gen- 

 erally toothed or folded within ; hinge with two oblique cardinal 

 and two marginal teeth in each valve ; pallial impression without a 



sinus. 



Cardium Islandicum. 



Fig. 58. 



Shell large, rounded-ovate, tumid, sub-equipartite, with about thirty-six sharp, 

 three-sided ribs ; epidermis lax, and rising into a fringe on the angle of the ribs. 



Cardium Islandicum, Lin. Syst. Nat. 1124. — Chemx. vi. 200, t 19, fig-. 195. — Gmelin, 

 Syst. 3252. — Brug. Encyc. Me'tli. 222. — Wood, Gen. Conch. 225, pi. 55, figs. 2, 

 3; Lulex, pi. 5, fig. 27. — Lister, Conch, t. 329, fig. 166. — Gu.vlt, Test. t. 71, fig. 

 M. — KxoRR, Delices, &c. vi. t. 8, fig. 3. — Borx, Mus. 49. — Sowerby, Conch. 

 111. No. 194. — MiDDBND. Beitr. z. Malac. Ross, ill. 38. — Stimpsox, Shells of New 

 England, 19; Inv. Gr. Manan, 21. 



Cardium arcticum, Sowerby, Conch. 111. fig. 26 (1841). 



Cardium ciliatum, O. Fabr. Fauna Gnenl. 410 (1780). — Moller, Moll. Gn^'ul. 20. 



Cardium pubescens, Couthouy, Bost. .Tourn. Nat. Hist. ii. 60, jil. 3, fig. 6 (young). 



Shell large, rather thin, nearly equipartite, a little obliquely 

 rounded-ovate ; tumid ; anterior part shortest and narrowest, ends 

 regularly rounded ; Ijeaks prominent, the points turned inwards, 

 and nearly in contact ; in front of them is a narrow, heart-shaped 

 depression ; on each valve are thirty-six, or more, three-sided, sharp- 

 edged, radiating ribs, the furrows between them rounded, and reg- 

 ularly wrinkled by the lines of growth ; epidermis yellowisli-1)rown, 

 lax, and bristling into a stiff fringe on the sharp edge of the ribs 

 within straw colored, the portions covered by the mantle pearly 

 grooves, answering to the ribs without, are obvious within, and the 

 edges are strongly notched. Length, two inches; height, some- 

 what less ; breadth, one incli. 



