Shell « equivalve, thin-walled, and elongated oval in shape. » It is « composed of aragonite, and exterior sculpture is typically glossy and smooth, with fine lines. » (Cretaceous Atlas).
 

« Minute, strong, robust shell with concentric ridging; equal number of teeth on either side of the umbo; teeth taxodont and extend along the hinge to the level of the posterior edge of the adductor muscles; umbos low in profile and medially directed; internal ligament amphidetic and bean-shaped; […] This genus differs from Pristigloma, in that the hinge is symmetrical on either side of the umbo, having a robust shell, chevron-shaped teeth only and an internal amphidetic ligament. » – Sanders & Allen: “Studies on deep-sea Protobranchia (Bivalvia); prologue and the Pristiglomidae”, Bulletin of the Museum of Comparative Zoology at Harvard College vol.CLXV, Cambridge 1973, p.247.
 

« This group includes a large number of small, mostly deep-sea species, with glossy, iridescent, ovate, and usually wedge-shaped shells, nearly always having a slight postero-ventral sinuosity, which feebly defines an obscure, blunt, rostral region, without any definite carination. The shells do not gap, but close tightly, except that at the rostral angle of some species there may be a slight divergence. The internal cartilage, which is often relatively large, occupies a simple notch, which interrupts the hinge margin more or less completely and generally shows externally in a dorsal view; the notch usually terminates within on the inner or inferior surface of the hinge plate and is often bounded within by a slight ridge. A weak external ligament is present on the postero-dorsal margin. A relatively small, pallial sinus has been observed in several of the species, but is usually indistinct. » – Verrill & Bush: “Revision of the genera of Ledidae and Nuculidae of the Atlantic coast of the United States”, American Journal of Science ser.4, vol.III, New Haven 1897, p.55-56.