Diagnosis: Shell moderate (14.6 mm), b/l 0.38, a/l 0,42, whorls markedly convex, strongly impressed below suture, with a distinct but rounded shoulder, periphery median; siphonal canal rather long and narrow, its tip slightly obliquely truncate, unnotched; fasciole absent, anal sinus moderately deep, with somewhat parallel sides, parietal pad a small, angular nodule, at mid-paries; labrum with about 13 irregular ridges inside; subsutural cord absent: axial ribs opisthocline. terminating at shoulder slope, 11 on penultimate whorl, not nodulose, spiral lirae even, 17 on penultimate whorl, no intermediary or microspiral threads, but distinct microscopic granules in intervals and below suture; a single varix behind lip. Uniform yellowish-white.
Description: Shell fusiform (b/l 0,38, a/l 0,42). with moderately long, tapering, slightly obliquely truncate siphonal rostrum, bent slightly to right, and a relatively high spire, suture fairly shallow, slightly undulating; teleoconch whorls about 8£; whorls convex, periphery more or less median, with terminations of axial ribs forming a slight shoulder; shoulder slope gently concave, without a shoulder sulcus or subsutural cord; left side of base of body whorl moderately concave, fasciole absent, without a false umbilicus. Aperture narrowly pyriform, with greatest width at about posterior third, siphonal canal wide, flaring slightly towards end, its termination only slightly oblique and not notched; labial callus fairly thin, its outer edge barely free on columella, forming a small, angular nodule situated about halfway down parietal region, not constricting anal sinus; columella only slightly convex; inner margin of labrum with about 13 short, irregular ridges; anal sinus rather deep, U-shaped with somewhat parallel sides, directed outwards.
Sculptured by strong axial ribs, crossed by narrow spiral lirae which are of uniform strength, without intermediaries or microspiral threads; interstices and entire subsutural region with microscopic pustules; a single low varicoid rib immediately behind lip. Axial ribs evanescing abruptly above shoulder, less abruptly on early whorls, on body whorl reaching upper part of rostrum: ribs moderately opisthocline, slightly wider than intervals, crests rounded in cross-section, sides moderately steep; about 9 ribs on 1st whorl, 11 on penultimate one. Spiral lirae flat-topped, more or less equal to their interstices, 3 threads on lower half of 1st whorl, on penultimate whorl 14 below shoulder. 5 thinner lirae above shoulder, base of body whorl with about 28 lirae. those on rostrum close and rounded. Colour uniform yellowish-white.
Dimensions: 14,6x5,6 mm (holotype).

AS MANGILIA BENJAMINI BARTSCH
Shell elongate-conic, flesh colored. Nuclear whorls, more than one, smooth. Post-nuclear whorls strongly rounded; the sinus falling at the summit where the whorls are somewhat contracted; surface of the post-nuclear whorls marked with strong, rounded, protracted axial ribs, which begin practically anterior to the sinus and extend strongly to the periphery; they are scarcely defined anterior to this on the last whorl. Of these ribs 10 occur upon the first to fourth, 12 upon the fifth to seventh, and 14 upon the penultimate turn. The axial ribs are about as wide as the spaces that separate them. In addition to these axial ribs the whorls are marked by numerous slender spiral threads, of which about 5 occur in the area of the sinus on the last three turns. These are finer than those which cover the rest of the turn between the sutures; of the latter 3.occur upon the first to third, 4 upon the fourth, 7 upon the fifth and sixth, 11 upon the next, and 13 on the last turn. The spaces between the spiral threads about equal the spiral threads in strength. The surface between the spiral threads is covered with fine granulations on the spire. The last whorl anterior to the periphery is marked by 27 spiral cords, which are about equal and equally spaced, being only a trifle stronger on the columella. Sutures well constricted; aperture with a strong deep sinus at its posterior angle, which renders the outer lip, anterior to this, decidedly claw-like; outer lip strongly reenforced within by a callus which bears about 15 denticulations on the inner surface. Columella and parietal wall glazed with a thin callus.
The type, Cat. No. 210, U.S.N.M., was collected by William Stimpson on the North Pacific Exploring Expedition at False Bay. It has nine post-nuclear whorls and measures: Length, 15.3 mm.; diameter, 5.7 mm. The specimen was labeled Clathurella gracilis Montagu. It differs from this in being uniformly smaller and having ever so many more spiral cords. Named for Dr. Marcus Benjamin of the United States National Museum.

South-Africa. False Bay.