Shell flat, equivalve, somewhat inequilateral; ligament internal.
 

Synonym Syndosmya Récluz, who writes: « Shell equivalve, inequilateral, transverse, having an epidermis, oval, oblong or subtriangular, thin, anteriorly rounded; angular, flexible and more gaping on the posterior side, which is the shortest. Umbones small, slightly protruding, slightly reflected inside or posteriorly. Hinge with two small, thin, almost parallel cardinal teeth on the right valve, and only one on the left valve, articulated with the other two; an oval or subtrigone spatula, very short, is juxtaposed on the upper and posterior internal edge of the two valves for the ligament; two lateral lamellar teeth, on the right valve, very rarely on the left. Ligament double: one external, short, thin, narrow and fibrous; the other one internal, stronger, cartilaginous, fixed in the cardinal fossulae. Muscular impressions oblong, curved and sharp at the top. Excavation of the mantle transverse, very deep, oval-triangular, with rounded angles. » – C. A. Récluz: “Monographie du genre Syndosmya”, Revue Zoologique vol.VI, Paris 1843, p.359.
 

« Shell equivalve, with a single tooth inserted between two obsolete ones. » – W. Turton: Conchylia insularum britannicarum, London 1822, p.359. « The Genus seems allied to the Crassatella of Lamarck » (op. cit. p.56).
 

« Shell oval or triangular, more or less swollen, not very gaping. Hinge: in the left valve two linear, divergent, slightly protruding cardinal teeth; in the right valve a linear cardinal tooth a little oblique and slightly projecting. In each valve in front of the teeth ,a sigmoid or triangular fossula, oblique, with a callus projecting in front. » – C. F. Schumacher: Essai d’un nouveau système des habitations des vers testacés, Copenghagen 1817, p.127.