Original Description: "O. testa hyalina margine acuta: radiis tenuissimis, squamularum arcubus concentricis." (fide Gmelin, 1791)
Additional Description: Shell thin, translucent, convex and inequilateral; right valve slightly more convex than left. Overall convexity may vary from moderate to strong. Surface sculpture may vary from nearly smooth to consisting of fine radiating grooves and concentric lines. Auricles unequal. Coloration clear to white. Size: Normal adult size range is 15 to 25 mm.

Description. - Shell thin, translucent, higher than wide. Valves inequilateral, right valve slightly more convex than left one. Except for fine teeth along inner margin of the ctenolium, 2 or 3 ribs consisting of fine tubercles present. Anterior auricles 1.21-1.34 times as large as posterior ones. Microsculpture of very fine radiating grooves and irregularly set concentric ridges, latter ornamented with tuberculous outgrows. Microsculpture continued on auricles, with exception of anterior auricle of right valve, which has 5-6 ribs composed of more or less scalelike tubercles. Byssal notch broad, as well as ctenolium. Resilium triangular and very small. Top angle varying from 79°-87°. Shell translucent white. Dimensions. - The largest specimen at my disposal measured 19.9 mm heigh x 18.6 mm wide x 7.9 mm deep.
Distribution. - This species can be found troughout the Atlantic and Pacific Arctic region, as well in deeper waters along the coasts of western Europe, the Mediterranean, and along the West African coast south to Walvisbaai, Namibia. The species is also known from the Indo-Pacific and the American coasts. Habitat. - This species inhabits the fine muddy bottoms exposed to cold water. In the Arctic it can be found at considerable less depth (30-700 m) than in southern Europe and the Mediterranean (400-3000 m). Remarks. - This species is rather variable in the tuberculation and thickness of its shell, subsequently receiving many varietal names. As all forms or varieties are represented in the larger samples examined, it serves no purpose to maintain these names.

Distribution: Found throughout the Atlantic Ocean, from the Arctic to the Antarctic. Also reported from the Mediterranean Sea and from the eastern Pacific along the coast of Chile. Habitat: Sublittoral zone to deep water, on muddy bottoms. Remarks: There is still a great deal of research required on D. vitreus. No two authors agree on its distribution.