Shell orbicular, solid, almost white, with a long and narrow anterior muscle scar; « two teeth in each valve, with lateral teeth. » –J. Fleming: A history of British animals, London 1828, p.441.
 

Shell small, equivalve, inequilateral, often tumid; beaks prominent, ligament and resilium external; posterior lateral teeth distinct; margins usually crenulate (Dall, 1901).
 

Shell small, orbicular, equivalve, inequilateral, thin, whitish, moderately convex; lunule small, cordate, deeply excavated; sculpture made of irregular growth marks, sometimes crossed by minute radials; posterior and ventral margins rounded, anterior margin a little excavated near the umbones; beaks prominent, ligament internal (Poli, Dautzenberg).
 

« Shell tumid, orbicular, extremely thin; hinge without teeth. » – T. A. di Monterosato: Nomenclatura generica e specifica di alcune conchiglie mediterranee, Palermo 1884, p.17. The shells are not always as fragile as Monterosato says. Hinge completely toothless.
 

« Valve with oblique sculpture; hinge provided with lateral teeth. » – T. A. di Monterosato: Nomenclatura generica e specifica di alcune conchiglie mediterranee, Palermo 1884, p.18.
 

« Shell usually large, lentiform, white, with a conspicuous periostracum, concentrically lamellose or striated; the cardinal teeth developed, the inner pair usually bifid; the laterals obsolete or absent, the inner margins entire. This is a well-marked group with extensive geographical and geological distribution, inhabiting preferably cold waters and frequently abyssal depths. » – W. H. Dall: “Synopsis of the Lucinacea and of the American species”, Proceedings of the United States National Museum vol.XXIII, Washington 1901, p.806.
 

« Shell subcircular to irregularly oval to subquadrate, the anterior margin often broadly angular. Surface sculpture of concentric growth lines only. Lunule either indistinct or small and heart-shaped. Hinge often thick but without teeth and sometimes with irregular folds on anterior ventral edge of hinge plate. Anterior adductor muscle scar elongate and detached from the pallial line for about two thirds of its length. Inner shell margin smooth. In large, thick-shelled specimens the trace of the pallial blood vessel may be deeply incised and inside of the shell often irregularly pustulose. » – Glover & Taylor: “New species and records of Rastafaria and Megaxinus (Bivalvia, Lucinidae) from the Western Indian Ocean and Red Sea, with a reappraisal of Megaxinus”, Journal of Conchology vol.36, London 1998, p.8.
 

« Shell oval-triangular, equivalve, nearly equilateral, closed. Hinge of one valve with a single tooth and lateral one each side; of the other valve with two teeth, the lateral ones obscure. Ligament external. » – W. Turton: Conchylia insularum britannicarum, London 1822, p.133.