« Shell equivalve, pectiniform, auriculate, most often gaping, usually white, free or fixed by a byssus. […] the shell is rarely equilateral but, in most of cases, it is slanting anteriorly, while, in the other Anisomyarian (Aviculidae or Mytilidae), when inequilateral it slants posteriorly. Beaks pointed, distant to each other, leaving exposed a part of the ligamentary area. Hinge edentulate or, in some cases, with traces of a taxodont teething consisting of a pair of denticles placed on each side of the fossula. Pallial line entire. A single muscular impression. » – E. Lamy: “Révision des Limidae vivants du Muséum National d’Histoire Naturelle de Paris”, Journal de Conchyliologie vol.74, Paris 1930, p.89-90.
 

Shell large, with thin valves devoid of anterior auricle.
 

« Valves compressed to slightly convex, thick-shelled. Anterior side straight, strongly impressed or flattened, the anterior ear small. Ribs relatively few, large, straight and coarsely scaly. » – A. A. Olsson: Mollusks of the tropical eastern Pacific, Ithaca 1961, p.169.
 

Shell subovate to oblong, thin, gaping anteriorly; auricles small, anterior side straight, posterior margin round; radials thin, neither spines nor scales.
 

Shell equilateral, ovate, convex, with a sculpture of strong radial costae; ears almost fused in the margins. Valves not gaping.
 

Shell small, not gaping, with a taxodont hinge and almost no ears.