Shell thin, white, with a high, acute spire and strongly carinated whorls. Whorls seven to eight, strongly convex, angulated by the sharp revolving carinas, of which there are usually three very prominent ones on the whorls of the spire. The upper one of these is situated at a considerable distance from the suture and forms a prominent shoulder, above which the surface of the whorl is somewhat concave and covered with several much finer, raised, spiral lines, of which one, usually at about the middle, is a little more prominent than the rest; the second carina is situated below the middle of the whorl and is separated from the upper one by a broad, concave interspace, which is covered by rather fine, distinct, raised spiral lines, separated by very distinct grooves of about the same breadth ; the third carina is usually situated just above the suture, but is sometimes concealed by it; it is separated from the second carina by a concave, spirally lined interspace, a little narrower than that between the first and second carina. On the last whorl there are usually two or more similar, but somewhat less prominent, carinae below the middle of the whorl, and the surface is everywhere covered by regularly spaced spiral lines or cinguli and grooves. Aperture rather small, somewhat semicircular; the outer lip is nearly regularly rounded from the suture to the base of the canal, but is slightly angulated at the carinae. In some of the larger specimens it somewhat recedes, and is slightly everted just below the suture. The canal is short, somewhat narrowed, nearly straight, or sometimes with the anterior end a little everted. The columella is nearly straight, its inner margin having a slight sigmoid curvature; the inner lip is covered by a very thin coat of smooth enamel, which extends out only a slight distance be-yond the edge of the lip, with a broadly curved outline. The nuclear whorls are small and regularly spiral, consisting of rather more than two turns, and have the surface smooth and glossy. On the succeeding whorl there are about four distinct carinae. The epidermis is inconspicuous or wanting. The operculum is rounded-elliptical, considerably smaller than the aperture, with the nucleus situated near the outer edge, in front of the middle. The animal is destitute of eyes; the tentacles are long, slender, and gradually tapered.

There is some degree of variation in the proportions of the shell, but the absence of eyes is a good character distinguishing B. abyssorum from B. kjennerudae. The sculpture is also different in the two species. B. kjennerudae lacks the strong, sharp spiral keels characteristic of B. abyssorum and has evenly rounded ridges instead.

On the lower pari of ihe continental slope, from N Carolina to SW Greenland (Thorson, 1951), SW of Iceland and W of Ireland. Depth range 1400—2900 m.