58 



C. edule. The edible Cardium, or common Cockle. PI. 

 10, fig. 2. 



Species not gaping^ with about twenty-six depressed ribs 

 and transverse obsolete scales ; of a cream colour ; beaks 

 protuberant. 



C. cardissa. Venus's Heart. 



Species heart-shaped, valves angularly flattened, umbones 

 alternating. 



C. Icevigatum. The smooth Cardium. 

 Species smooth or nearly so, anterior side as large as the 

 posterior. 



C. hemicardium. The half-heart Cardium. 



Species ribbed, with elevated rough striae ; the anterior 

 side is very short and almost flat. 



C. costatum. The high-ribbed Cardium. 



No angle at the umbones ; anterior side at least as large as 

 the posterior ; rows of white, hollow, elevated ribs, situated 

 at regular distances, proceeding from the umbones to the mar- 

 gin, with the spaces between them of a reddish brown colour. 



C unedo. The Strawberry Heart. 



Species with ribs armed with small crescent-shaped 

 scales. 



