"Shell thin, ashy white externally, internally semi-nacreous; rounded with a comparatively short straight hinge-line; attached valve unknown; upper valve indistinctly auriculate, rather flat, irregular toward the margin with a small pointed but not prominent apex, a little to the right of the middle of the hinge-line; sculpture composed of somewhat irregular radiating costae, not bifurcating but increasing by intercalation toward the margin, where they are much crowded; these costae are formed by crowded overlapping rounded scales, like biscuits piled one over another, and showing sharp edges only where worn; there are about forty with a somewhat smaller number of intercalary ones; the concentric sculpture is composed of ill-defined lines of growth, and the whole surface is microscopically granulose; interior polished, silvery, reproducing the external rugulosites; muscular impressions invisible; cartilage pit triangular, distinct, hinge-line smooth, margin nearly simple." (fide DM, 1886) Size: Normal adult size range is 25 to 30 mm.

Only known from St. Vincent and the Islands.
Habitat: Deep water, fine sandy and muddy bottoms.