(da Costa, 1778)
Description (shell):
Shell elongate, conical, up to 16 (usually 10-12) moderately tumid whorls; apex pointed. Sculpture of strong costae and spiral striae, interacting to give oval tubercles: four rows on lower whorls, three on upper whorls; no tubercles on lowest spiral ridge of each whorl, or on basal ridges of last whorl. One costa, the varix, often more prominent than rest; varix of last whorl close to aperture. Aperture oval, drawn out to a short sinus basally; outer lip crenulate, without anal sinus. Inner lip reflected over columella region and base of last whorl; no umbilicus (B. reticulatum-drawing).
Size:
Up to 15 x 6 mm, commonly half this size.
Colour:
Buff to light chestnut-brown; tubercles, varices, and columella lighter.
Animal:
Snout long, bifid; cephalic tentacles long, slender with eyes on prominent bulge at base. Mantle edge broadly lobed; foot long, narrow, with doubled-edged anterior margin; large opercular lobe projects posteriorly from below oval operculum.
Habitat:
On soft substrata, associated with Zostera and other weeds; from LWST to 250 m.
Distribution:
Locally abundant. Widely distributed from Canaries to Lofoten Isles; absent from continental shores of the southern North Sea and east Channel (Distr. B. reticulatum).