DIAGNOSIS. Shell: Rather small, spire low, whorls flat-sided, with persistent long spines on all whorls. Body whorl with strong peripheral angle bearing 10-15 triangular, hollow spines, the posterior edges of which are at right angles to shell and form main part of spine. Basal angle rather weakly gemmate, area between it and peripheral angle slightly concave with single very weak spiral thread. Six weakly beaded spirals on upper surface of whorls, 3 on base below basal angle. Growth lines prosocline, fine and sharp. Basal callus very narrow, merely a thickened rim against columella, white. Surface yellowish-white with radial wine-red streaks dorsally and ventrally, and small spots on the gemmae of the spiral threads.
Operculum: Very thick and convex, sides weakly concentrically striated, lightly concave, centre a deep, narrow depression; the raised marginal portion appears to be a tight spiral and is weakly pustulose; white.
DIMENSIONS. Holotype: height 20 mm, diameter 22 mm (excluding spines); figured specimen: height 15.1 mm, diameter 28.35 mm (including spines), 18.5 mm (excluding spines).
TYPE LOCALITY. Off Kagoshima Bay, Japan, 188 m, "Albatross" Stn 4936. HOLOTYPE. USNM, 110507.
OTHER MATERIAL EXAMINED. Japan: Off Tosa Bay, Shikoku, 200 m (NSMT) (1); 34°28.3'N, 139°11.4'E, 110 m (Tokai Regional Fisheries Lab.) (1); Zenisu Stn 32, near Izu-Shichito Ids, 113 m (Tokai Regional Fisheries Lab.) (1).
OTHER LOCALITIES. Off Kii Peninsula, Japan (Oyama & Takemura, 1960); "rather rarely collected from Tosa Bay, Shikoku to Kyushu at depths of 50-200 m" (Habe, 1964, p. 21). Okutani (1972, p. 77) gave the distribution as from Kagoshima Bay eastwards to Zenisu Bank, probably in 100-200 m.
This relatively small, very long-spined species is related to the B. guttata complex. The spines are markedly longer and fewer (10 to 15 on the last whorl), the granular sculpture is finer, the subsutural channel weaker, and the axial growth lamellae more indistinct than in related species.