Shell ovate, conical, rather ventricose, thin white; whorls ventricose, closely transversely plaited, and deeply and closely spirally striated, the upper one with a subpostcrior, and the last with three or more elevated keels. Mouth ovate, inner lip much absorbed; canal only slightly recurved. (Gray.)
This shell is very like B. glaciale in form, but the whorls are deeply striated and closely plaited. The shells of this kind appear to be formed of two coats, an opaque dead-white external one, and a hard pellucid-white inner one; the outer one is often eroded, from the apex of the Polar species leaving the under one exposed, which being smooth, polished, and without striae give the tips of the shell quite a different appearance from the rest. In one specimen the last whorl has three equidistant keels—in the other the hinder keel is prominent, and there are three close, slight keels in front. There was a fragment of a shell brought from the same place with the former, which is deeply spirally striated, longitudinally plaited, and slightly keeled like the former, but it is rather more solid, more deeply striated, and the whorl has an extra strong prominent keel just before the suture, which gives the shell a very different appearance. I am inclined to consider it only a variety of this species. (Gray.)
TYPE in British Museum? Type locality, Icy Cape, Arctic.
RANGE. Arctic Ocean to Bering Sea; also Alaska.