Shell inflated, equivalve, sub-cordiform (when seen anteriorly), generally costated from the summit to the circumference; summits very evident; slightly recurved forward; hinge complex, similar, formed by two oblique cardinal teeth, articulating with the corresponding teeth on the other valve; two distant lateral teeth on each valve; ligament dorsal, posterior, and very short. Cardium costatum. C. Indicum. C. ringens. C. Asiaticum. C. tennicostatum. C. fimbriatum. C. pseudolima. C. aculeatum. C. erinaceum. C. tuberculatum. C. Brasilianum. C. apertum. C. papyraceum. C. bullatum. C. ciliare. C. echinatum. C. lævigatum. C. biradiatum. C. eolicum. C. pectinatum. C. isocardia. C. muricatum. C. angulatum. C. marmoreum. C. elongatum. C. ventricosum. C. rugosum. C. sulcatum. C. serratum. C. unedo. C. medium. C. fragum. C. retusum. C. tumoriferum. C. rusticum. C. edule. C. Groenlandicum. C. latum. C. crenulatum. C. exiguum. C. minutum. C. roseum. C. scobinatum. C. hemicardium. C. cardissa. C. inversum. C. Junoniæ. C. lineatum. _C. edule._ The edible Cardium, or common Cockle. Pl. 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. lævigatum._ 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 striæ; the anterior side is very short and almost flat. _C. costatum._ The high-ribbed Cardium.