Shell small to large, equivalve, inequilateral; valves convex, often carinate (genus Glosssocardia), with strongly coiled prosogyrate umbones.
 

Shell large, globose, with a brownish periostracum; synonym Isocardia Lamarck, who writes: « heart-shaped, with beaks distant to each other, coiled, diverging; two flat cardinal teeth, one lateral tooth isolated under the escutcheon. » – J. B. M. de Lamarck: “Prodrome d’une nouvelle classification des coquilles”, Mémoires de la Société d’Histoire Naturelle de Paris vol.I, Paris 1799, p.86. Ligament external; muscle scars large, placed near the anterior and posterior extremities. The genus is monospecific.