Shells inequilateral, suboblong to elongate, gaping at one or both ends; hinge bearing a large spatulate tooth; ligament internal.
 

« Shell bivalve, transverse, gaping at both ends. One large cardinal tooth on the left valve, compressed, broad, somewhat rounded, projecting almost vertically. A cardinal pit on the other valve. Ligament internal, short and thick, inserted in the projecting tooth, and the corresponding cavity of the opposite valve. » – J. G. Children: “Lamarck’s genera of shells”, Quarterly Journal of Science, Literature and the Arts vol.XIV, London 1823, p.84.
 

Sherll very variable in shape, « transverse, inequivalve, inequilateral, open at the anterior end. Hinge of the left valve with an elevated transversely dilated tooth, of the right valve with a concave tooth and small denticle behind it; lateral teeth none. Ligament internal. » – W. Turton: Conchylia insularum britannicarum, London 1822, p.36.