CARDIUM.— Cockle or Heart-shell. 



Animal — a Teihys: Shell bivalve, nearly equilateral^ equi- 

 valve, generally convex, longitudinally ribbed, striated, or 

 grooved, with a toothed margin ; hinge with two teeth- 

 near the beak, and a larger remote lateral one on each 

 side, each locking into the opposite. 



This genus, though not so numerous as the last, contains 

 great variety of structure and coloring. There are fifty- 

 two species. 



The valves of the Cardium are for the most part of a 

 convex, swollen, or gibbous construction, and almost or- 

 bicular; yet, in some instances, their form is elongated 



