423 MOLLUSCA. CARDIADiE. Cardium. 
435. C. elongatum. — Shell, rounded, compressed, with about 
25 flattened prickly ribs. 
Mont. Test. Brit. 82. Turt. Biv. Brit. 185. t. xiii. f. 8.— Devonshire and 
Zetland. 
Shell about a quarter of an inch in diameter : produced, and a little angu- 
lar at the cartilage side ; the spines are broad and thin, corresponding with 
the size of the ribs. 
436. C. exiguum. — Shell subtriangular, retrally truncate, 
with from 20 to 22 tubercled ribs. 
Pectiinculus exiguus, List. Conch, t. cccxvii. — Cardium subcordatum, 
Walker's Test. Min. 23. t. cxi. f. 83. — C. pygmseum, Dm. Brit. Shells, 
t. xxxii. f. 3 — C. ex. Mont. Test. Brit. 82. Turt. Biv. Brit. 187 — ^ 
Various parts of the coast from Devon to Zetland. 
About half an inch in diameter, transversely striated ; the ribs rounded 
with a mesial ridge, the tubercles are short, and somewhat arched. 
Ribs armed with transverse scales. 
437. C. edule. — Common Cockle. — Shell somewhat globular, 
with about 26 ribs, rounded and interruptedly sulcated trans- 
\ersely. 
Pectunculus vulgaris. List. An. Ang. 189. Conch, t. cccxxxiv — Car., 
dium edule, Linn. Syst. i. 1124. Penn. Brit. Zool. iv. 91. t. 1. f. 41. 
Mont. Test. Brit. t. 76. Don. Brit. Shells, t. cxxiv. f. 1, 2. Turt. 
Biv. Brit. 188. — Common in sand, near low water-mark. 
Diameter about 2 inches, yellowish-white ; nearly equilateral, or produced 
posteriorly ; and more or less rugged by the layers of growth. — Cockles form 
a very palatable food, either raw or boiled, and are considered in highest 
season in the spring months. 
438. C. Jasciatum. — Shell slightly compressed with about 
26 ribs ; those in the middle smooth, the extreme ones scaly. 
Mont. Test. Brit. Sup. 30. t. xxvii. f. 6. Turt. Biv. Brit. 189. — ^Various 
parts of the coast. 
Diameter |ths of an inch ; nearly equilateral, whitish, Avith irregular ru- 
fous bands ; the ribs are a little flattened ; the thin transverse scales some- 
times extend in front along the margin. 
unarmedj. 
439. C. medium. — Shell subtriangular, truncated retrally, 
with a prominent line of junction ; ribs about 36. 
Pectunculus subrufus, Zwf. Conch, t. cccxvi — C. med. Linn. Syst. i. 1122. 
Don. Brit. Shells, t. xxxii. f, 1. Mont. Test. Brit. 83. Turt. Biv. 
Brit. 189 English coast, rare. 
Length upwards of an inch ; yellowish-white, with brown blotches ; ribs 
flattened, furrows crossed by fine striae. This species is common to the Me- 
diterranean and West Indies. The specimen figured by Donovan from Har- 
tlepool, and another, referred to by Dr Turton, as taken alive at Torquay, 
are the only instances as yet recorded of its occurrence in our seas. 
