« Free or weakly byssate Pectinoidea with outer foliated calcitic layer on left valve and prismatic calcitic layer on main part of right valve disc. Inner layer crossed-lamellar aragonite beyond pallial line, in some species nearly to distal margins. Byssal notch without ctenolium. » – H. K. Dijkstra: scallop.nl.
 

« Shells thin, rounded, scarcely oblique, with symmetrical auricles and simple margins. The two valves are unlike in sculpture. The right valve is a little flattened and upturned at the flexible margin, so as to fit tightly against the upper valve. The thin lower valve has, in the typical species, regular, thin, elevated, concentric lamellae, which aid in the adaptation of the edge to that of the upper valve; the margin is usually flattened or bevelled. The upper (left) valve is radially sculptured, rarely smooth; it usually has radial rows of arched scales, pustules, or points, and also concentric raised lines; it is sometimes cancellated. No radial ribs, nor interlocking points at the margin. Auricles well developed, subequal, angulated and well-defined at both ends; byssal notch well defined; few or no pectinidial teeth. Cardinal folds single, rather feebly developed, often cross-lined. » – A. E. Verrill: “A study of the family Pectinidae, with a revision of the genera and subgenera”, Transactions of the Connecticut Academy of Arts and Sciences vol.10, New Haven 1899-1900, p.70. The species live in deep water.
 

Shell very small, thin, semitransparent, orbicular, smooth with the exception of some radial and concentric micro-striae. The auricles are of almost equal size. The genus is monospecific.