C. mixta. C. abbreviata. C. plicatina. C. flexuosa. C. macrodon. C. lunularis. C. squamosa. C. lunaris. C. cardilla. C. cygnus. C. dentaria. _C. Chione._ The Chione Cytherea. Thick, solid, heart-shaped, covered with a smooth brown epidermis, beneath which the shell is of a beautiful purple; radiated longitudinally, faintly wrinkled transversely, anterior cardinal tooth entire, and without a striated canal; apex turned sideways, with a cordiform depression. _C. mactroides._ The Mactra-like Cytherea. Pl. 9, fig. 4. Species thin, convex, triangular; summits very marked; margins sharp; anterior cardinal tooth entire. _C. pectinata._ The pectinated Cytherea. Species oval, thick, solid, more or less compressed, costated, pectinated upon the edges. 6. Venus. Eighty-eight species. This genus of shells is numerous and varied. It surpasses all bivalve shells in beauty, and is in form very like the Cytherea, but easily distinguished by the hinge, which almost invariably contains three approximate teeth, and a lateral tooth diverging to the summit. The internal margin of the valves is crenated or dentated, with or without lamellar striæ. The shells are of the most beautiful and lively tints; the exterior as well as the interior colouring is of almost every possible shade and hue. They are found buried a little below the surface on the sandy shores of most parts of the world, particularly in warm climates. Shell solid, thick, regular, perfectly equivalve and close, more or less inequilateral; summits well marked, inclined anteriorly; hinge sub-similar; the middle cardinal tooth forked, or three cardinal teeth more or less contiguous and convergent towards the summit; ligament thick, often arched, convex, and exterior; two distant muscular impressions; cordiform depressions beneath the beaks.