Type locality: Norway, Sarpsborg, Fredrikstad; Pleistocene, Yoldialerets Fauna. Description: Shell small for the genus (usually between 52 and 76 mm, occasionally up to 107.9 mm), rather thick, solid. Colour red-brown, spirals white or with white streaks on top. Shell occasionally uniformly white. Shape usually angulate with strong carina on shoulder (shallow water), whorls occasionally convex (deep water). Upper spire whorl with 2, body whorl with 7 or 8 spiral cords which are variable in strength, ranging from fine to strong, usually forming a carina on shoulder, occasionally forming 2 projecting peripheral keels. Interspaces smooth or with 1,3 or 5 fine, rather sharp secondary spiral cords separated by a narrow interspace with planar bottom, central cord occasionally stronger. Axial sculpture consisting of fine incremental lines, occasionally some knobs on primary spiral cords. Range and habitat: Neptunea denselirata is an exclusively Arctic species. Its origin is in the Pleistocene Glacial of southern Scandinavia and it migrated northwards during the subsequent warming. Its present range is the Atlantic Arctic from the Northern Territories (Macpherson, 1971: 82, as Neptunea despecta and Neptunea despecta tornata var. denselirata), Baffin Sea (Uummannaq, West Greenland, KBIN, Dautzenberg Collection) in the east, Barentz Sea (from Svaldbard ("Spitzbergen") in the north to off the entrance to the White Sea in the south) via the Kara Sea to the Laptev Sea. The southern boundary of the range is limited by warm water from the North Atlantic Current (Gulf Stream). The northern and eastern boundaries of the range roughly follow the limit of the polar ice-sheet and are limited by the cold water from the Polar Sea and the influence of fresh water. Salinity and temperature fluctuations strongly limit distribution, which is why it is not found in the White Sea but near its entrance. Preferring the safety of deeper water in fjords and moderately deep basins, the shallow water shelf around the New Siberian Islands is the eastern barrier of the range. Living on mud with stones between 10 and 430 m deep in fjords (Golikov, 1963: 179) and on sandy-muddy bottoms in deep water of the western Barentz Sea (Spitzbergen Sea). This species can survive temperature fluctuations down to -1,6° C (Golikov, 1963: 65). Found sympatrically with Neptunea despecta in the western Barentz Sea (75° 40'-76° 20' N, 27° 50'-32° 10' E, southeast of Hopen Island, south of Svalbard, 350-400 m. deep) and syntopically with Neptunea despecta in the eastern Barentz Sea (70° 55' N, 44° 12' E, west slope of Gus Bank, trawled 225-243 m deep, on mud with gravel). Comparison: Neptunea denselirata exhibits remarkable variation in shape and sculpture and it is hard to produce a description which fits all specimens. The high and slender spire has a typical shape and sculpture. Some specimens have weak primary spiral cords and look like Neptunea despecta. Some specimens have one or two well-developed keels, in combination with almost smooth interspaces, and such shells are easy to confuse with Neptunea borealis. White shells are rare. Neptunea multistriata from the north Pacific and adjacent Polar Sea is similar in spiral sculpture but differs in having a broader shape with short spire, and broader secondary spiral cords with narrow interspaces. Neptunea vinlandica n. nom. from the western Atlantic has an almost identical shape, spiral sculpture ry spiral cords ed thin, fragile and and pattern as the deep water form but differs in the slightly broader secondary spiral cords with a narrow line as interspace (instead of an narrow and planar interspace) and by having 3 spiral cords on the upper spire whorls.