Shell ovate-conical, thin, horn-colored, with numerous transverse striae; the last whorl with three double bands (the upper one nearly obsolete) which are brown, irregularly spotted with white; columella smooth; margin of the labrum slightly reflected. Whorls eight, convex, finely and closely striated in a transverse direction; striae slightly waved, and crossed by very minute longitudinal lines. Bands on the lower whorl six, narrow, disposed in pairs, brown, irregularly spotted with white, gradually disappearing on the upper ones. Columella smooth, white; aperture horn-colored ; lip white, slightly thickened and reflected at the margin. Canal very short, with a slight tinge of violet behind it. Length 2; breadth, 1 mm. (Bennett.)
TYPE in British Museum? Type locality, harbor of Cork.
RANGE. "Northwest America" (Pease); exotic?

Shell. Superficially the shell is more like that of Colus spp. than B. undatum in having less swollen whorls and a smooth appearance to the naked eye. It is delicate, slightly translucent, and bluntly pointed; it lacks periostracum, and has about 7 whorls which meet at rather deep sutures lying below the periphery of the upper whorl. Though apparently smooth the surface bears many fine spiral lines with more, and finer, growth lines crossing them so as to produce a fine granulation. The growth lines are prosocline at the sutures but curve to become orthocline or slightly opisthocline.
The protoconch has 1.5 - 2.0 whorls which appear smooth and glossy but bear many microscopic spiral and growth lines. The change of pattern to the first postlarval whorl is abrupt. The initial chamber is large and flattened. The whole protoconch measures about 2.5 mm in height and diameter.
Aperture. A rather narrow and elongated oval, angulated adapically and tapering basally to the siphonal canal. Its greater breadth lies about halfway between these points. The outer lip starts normal to the surface of the last whorl, near its periphery; it curves smoothly to the canal, a little flexuous where it joins that. Its edge is thin, sometimes a little everted, and shows hardly any anal sinus. The canal is short and widely open. The columella is rather long and straight; the lip alongside it is out-turned to meet a degenerate siphonal fasciole. Over the last whorl the inner lip forms a callus sufficient to hide the underlying pattern.
Colour, While, cream, or pale tawny, sometimes marked with red-brown bands or rows of spots.
Size. Up to 40 x 22 mm. Last whorl = c. 70% of total shell height; aperture = c. 55% of shell height.
Animal. Like B. undatum. The operculum is small, triangular rather than oval. Colour. White or cream with black markings.
Geographical distribution. A northern species recorded from Norway and the coast of Sweden to Bohuslan. It has been found off the Shetlands, in The Minch, off the west and south coasts of Ireland; at greater depths south to Portugal and the western Mediterranean. It is rather rare.
Habitat. On soft bottoms from about 70 m to 1200 m deep.
food. Not known, but the animals are presumably predators and carrion feeders.

Along the European shelf and the uppermost continental slope, from Finmark (N Norway) (Sars, 1878) and E of Iceland (Oskarsson. 1977) to W Morocco (Locard. 1897) and the western part of the Mediterranean (Settepassi, 1977; Casamor & Ghisotti, 1968). The depth distribution is 15 m (Kattegat, ZMC) — 360 m (W Norway, coll. AW) in the northern part and 70 m (Casamor & Ghisotti, 1968) — 1190 m (Locard, 1897) in the southern part of the range.