CARDIUM. 139 



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

 deeply and regularly grooved, than G. g-cmma, 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 opeu, 

 siphons very short, foot very large and kneed. 



Genus CARDIUITI, Lix. 1758. 



Shell somewhat heart-shaped; beaks 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, Lix. Syst. Nat. 1124. — Ciicmx. vi. 200, t 19, fig. 195— Gmelix, 

 Syst. 3252. — Brug. Encyc. Mcth. 222. — Wood, Gen. Conch. 225, pi. 55, tigs. 2, 

 .3; Index, pi. 5, fi-. 27. — Lister, Conch, t. 329, fig. IGG. — Gu.vlt, Test. t. 71, fig. 

 M. — KxoKR, De'liccs, &c. vi. t. 8, fig. 3. — Born, Mus. 49. — Sowerby, Conc'i. 

 111. No. 194. — MiDDENi). Biitr. z. JNlalac. Ross, iil. 38. — Stimpsox, Shells of New 

 En,t;-laii(l, 19; Iiiv. Gr. iNlanan, 21. 



Cardium arctirum, Sowekby, Conch. 111. fig. 26 (1841). 



Cardium ciliatum, 0. F.vim. Fauna Gra-nl. 410 (1780). — Moller, Moll. Gr.rnl. 20. 



Cardium pubesccns, Coutiiouy, Bost. Joiirn. Nat. Ilist. ii. GO, pi. 3, fig. G (young). 



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

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

 regularly rounded ; beaks 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 ril)S, the furrows between them rounded, and reg- 

 ularly wrinkled by the lines of growth ; epidermis yellowish-brown, 

 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 inch. 



