DIAGNOSIS. Shell: Solid, with rounded body whorl and weakly convex spire whorls, weakly channelled suture, short spines and heavy, gemmate spiral cords. Peripheral angle low on whorls of spire, rounded on body whorl, with short, hollow spines, about 26 on body whorl. Basal angulation represented by the second basal spiral cord which is very slightly more prominent than the first. Five additional cords on base and 5 above periphery, the uppermost strongest. Growth lamellae fine and weak, strongly prosocline. Basal callus expands over ¼ of base, very thin, transparent, colourless, separated from the white columella by crescent-shaped depression. Outer lip slightly reflected and expanded. Surface pinkish-mauve, with small dark reddish-mauve blotches.
Operculum: Oval, white, with a slight depression off centre in adult, juvenile with marked central depression. Marginal area a narrow flattened rim, central area rather flat-topped, weakly pitted, sides of central area with few irregular concentric striae.
DIMENSIONS. Holotype: height 40 mm, diameter 39.4 mm; figured specimen: height 31 mm, diameter 33 mm.
TYPE LOCALITY. "Tatiyama", Japan (= Tateyama, Sagami Bay).
HOLOTYPE. BMNH, 1968210.
OTHER MATERIAL EXAMINED. Several of the specimens recorded by Okutani (1972) from three submarine banks near the Izu-Shichito Ids (Tokai Regional Fisheries Laboratory); Okinose Bank, off Sagami Bay, central Honshu, 48 m (NSMT) (1).
OTHER LOCALITIES. "Mainly found in Sagami Bay, Honshu at depths of 50-200 m" (Habe 1964, p. 21); Okutani (1972) noted that this subspecies may be one of the most common prosobranchs on the submarine banks near the Izu-Shichito Islands; six localities in Sagami Bay (Kuroda et ai, 1971, p. 48). The geographic range is Honshu (Sagami Bay to off Chosi City) and around the Izu Islands, on fine sandy and gravelly substrates in depths of 50-200 m (Kuroda et al., 1971). Recorded as a Pliocene fossil (B. amabilis) from Tyosi, Japan, by Ozaki (1954, p. 11); as noted by Habe (1958, p. 55) this name appears to be based on fossil specimens of B. guttata guttata.
Bolma guttata guttata differs from the other subspecies in its shorter spines and much coarser sculpture. Dr. Tadashige Habe noted (in litt., 8 Nov. 1975) that B. guttata millegranosa seems to be a subspecies of 6. guttata "from Sagami Bay", having a different operculum.

Three geographic subspecies are recognised as comprising this species. The overall features of similarity area prominent sutural channel, numerous, short peripheral spines and a rather weak basal angle. Only 1-3 spiral cords lie between the basal and peripheral angles. The basal callus is very thin and transparent, white, and separated from the columella by a shallow groove. The operculum is subcircular and has weak concentric striae around the edges of the central area which is weakly pustulose. The colour in all forms is mauve-pink, usually with a few purple blotches.
This species is very similar to B. marshalli (Thomson), which differs mainly in its stronger basal angle, finer sculpture and thicker and wider basal callus which is not separated from the columella by a groove. The operculum is also flatter and thinner. It also closely resembles B. persica (Dall) which, however, has a relatively shorter spire, much longer peripheral spines, weaker sculpture and no sutural channel.