Shell large, solid, rather thin, with about six whorls exclusive of the (decollate) nucleus; whorls full, rounded, slightly excavated in front of the appressed suture; sculpture of, on the last whorl, three sizes of flattish rounded threads, alternating regularly in size, but on the upper whorls of only two alternated sizes separated only by shallow grooves; transverse sculpture of moderately prominent incremental lines; aperture ample, the pillar lip blotched with livid pink and white, the pillar twisted, with a solid white inner edge and strong siphonal fascioie; canal moderate, slightly recurved; outer lip slightly crenulated by the sculpture, sharp, very slightly expanded; throat smooth, pinkish; epidermis very thin and translucent, closely adherent to the surface; operculum normal, light brown. Length of shell (decollate), 100; of last whorl, 80; maximum diameter, 56 mm.

Shell medium to large (up to 150.9 mm), thin but rather solid. Upper spire whorls sculptured with fine, rather sharp primary spiral cords, interspaces with fine, secondary spiral cords of different strength. Subsutural slope rather broad, slightly concave, depressed to preceding whorl.

Neptunea constricta differs in having slightly broader spiral cords and quite convex whorls with deep suture.

Bering Sea near the Pribilov Islands.

Neptunea insularis lives in the central Bering Sea (type locality) and western Pacific (off Shiranuka, Hokkaido). Most records by former authors are based on misidentifications and the range as found in publications has to be confirmed. Bathymetrical range deep, between 230 and 1000 m. Comparison: Neptunea insularis is characterized by the rather thin shell, covered by numerous spiral cords of different strength and the slightly concave subsutural slope.