WORMS. TESTACfeA 39. Cardium. 153 



neath the skin, generally deep red or variously marked, denticulate 

 on the margin within. 



226. C. edule. Antiquated, a little produced at one end, 

 with obsolete recurved scales, and about 26 depressed 

 ribs. 



Br. Zool. t. .Q0./,4i. Dowfv. t. 124. Da Cost. t. n.f.i. 



Shell hardly 2 inches wide, yellowish-white or bluish, rarely 

 equilateral, a little rough near the circumference. 



227. C. rusticum. Antiquated, a little produced at one 

 end, with about 20 remote ribs, the interstices rug- 

 ged. 



Donovan iv. t. 124./. 2. Barbut. t. $./. 12. 



Shell refemhling C. edule, except that it is larger, has an evident 

 ridge on the fore-margin when clofed, a narrow depressure behind 

 the beaks, the ribs fewer and more raifed, of a ferruginous or 

 livid colour, and bluish within. 



228. C. elongatum. Compressed, suboval, a little 'angu- 

 lar, somewhat elongated and angular on one side, with 

 21 faintly wrinkled and rounded ribs. 



Montague Brit. Shells, p. 82. n. 7. 



Shell a quarter of an inch wide, yellowish-white or light rufous : 

 beak not central, 



229. C. exiguum. Very convex, somewhat triangular, with 

 about 20 tubercled or wrinkled ribs, strongly striate 

 transversely in the interstices. 



Donovan, t. 32. /. 3. Walk, minute Shells/. 83. 



ShelL about half an inch wide, white or pale rufous, sloped on 

 the anterior side, and produced at one end. 



230. C. medium. Somewhat triangular, crenatc at the 

 sides, with about 26 smooth ribs. 



Donovan t. 32. /. i. Lister t. 3i6./. 153. 



Shell hardly an inch long, white variegated with chefnut, a little 

 truncate on one side and produced at one end : teeth one in each 

 valve, with strong lateral-ones. 



231. C. rubrum. Convex, smooth, glossy, pellucid, red: 

 hinge not quite central. 



Montague p. 83. Walk. min. shells. 862. 



Shell hardly 2 lines long, rounded at both end's, with the margin 

 plain: beak prominent : teeth nearly obfolete, the lateral-ones very 

 visible. 



232. C. discors. Very convex, suborbicular, glossy, 

 finely 5triate obliquely : hinge with 2 teeth in one 

 valve. 



Montague Brit. Shells, p. 84. n. it. 



Shell the size of a pea, white with fometimes a purple top, carna- 

 tion within ; the stria? reflected into an acute angle on the fore- 

 part; margin plain : beak central, leaning a little to one side: la- 

 teral teeth remote, laminate. 



33. C. muricatulum. Heart-shaped, opake, white, 

 muricatc on I he margin. 



Walk, min She II f. 84. Adams Microsc. t.\.f. 44- 

 Shell extremely minute, muricate in front. 



234. C. arcuatum. Orbicular, thin, brittle, scnii-pcllu- 

 cid, with fine regular transverse curved striae. 



Montague Brit. Shells, p. Sj. tab. %.f. 2. 

 Shetf not halt an inch wide, white, with a few irregular concentric 



