Shell acute conic, thin, of a subtranslucent brownish consistency (like B. castaneum Dall), with about seven turreted whorls; nucleus smooth, of two whorls; suture distinct, with wide channel in front of it, due to the first spiral rib; axial sculpture of faint incremental lines; surface with an extremely thin, smooth, dehiscent periostracum; spiral sculpture between the sutures of five or six strong, squarish, prominent, spiral ribs, with slightly narrower channeled interspaces, of which there may be from seven to ten on the last whorl; the posterior rib in many cases is nodulous or beaded, corresponding to little waves which at intervals may cross the sutural channel but do not seem ever to extend beyond the second rib; aperture semilunar, throat and body yellow, pillar and outer lip white; outer lip thickened, expanded, somewhat reflected, undulated by the ends of the ribs; a glaze of callus on the body; pillar straight, not pervious; canal wide, deep, recurved, forming a strong fasciole; oper¬culum small, rounded-triangular, the nucleus near the narrower end. Long, of type specimen, 54; of last whorl, 40; of aperture, 28; max. diam., 31 mm. (Dall.)
TYPE in United States National Museum, No. 110539. Type locality, Station 4777, Petrel Bank, Bering Sea.
RANGE. Petrel Bank, Bering Sea, in 42-54 fathoms.