Nuculana cestrota: Shell thin, compressed, elongated, rostrated, translucent white, with a pale gray or olive epidermis, which is generally mostly lost; umbones hardly raised above the hingeline, pointed, inconspicuous, compressed; base forming a shallow reversed arch, meeting the anterior curve of the upper edge in a rounded point; posterior upper margin nearly straight, becoming slightly concave toward the end of the rostrum; rostrum longest above, obliquely truncate, its basal margin slightly concave, then swelling into the curve of the base; sculpture of numerous thin, sharp, elevated concentric lamellae, prominent anteriorly and near the base, less so on the cheeks of the valves and obsolete near the rostrum; radiating sculpture of a ridge bounding the lunule over which the lamellae pass, becoming finer and then obsolete toward the pouting cardinal margin; also, a ridge bounding the escutcheon, and a second less obvious thread from the beak of each valve to the lower angle of the rostrum; the former shows by small elevated, pointed scales the influence of the lamellae*, slight traces of which also appear on the second ridge; the escutcheon is long, narrow, and smooth, with pouting lips, and there are no developed lamellae between the ridges outside of it; shell internally polished, showing no scars; there is no mesial ridge in the rostrum; cartilage large, black, triangular, posteriorly inclined, wholly internal; teeth small, about forty anterior and fifty posterior to the beaks, of which seven to nine on each side are undeveloped5 on the anterior side, between the anterior margin of the fossette and the tooth-line proper, is a flat space over which these undeveloped teeth are widened out as transverse, but little elevated, ridges; maximum longitude of shell, 25.5; longitude from vertical of beaks to end of rostrum, 17; maximum altitude of shell, 8.75; diameter, 3.75mm.

Nuculana cestrota: This is nearest N. costellata (G.B. I Sowerby, 1833), from New Zealand, but is proportionally more elongated and pointed posteriorly, and more compressed.

Nuculana cestrota: Panama. Near Colon (Aspinwall)