Diagnosis: Shell with decollated apex in shallow-water examples only, b/l 0,38-0,44, a/l 0,33-0,35, whorls strongly shouldered; axial ribs strong, 7-9 on penultimate whorl, with a strong subterminal varix; spiral sculpture of line, rounded threads, 8-11 on penultimate whorl; light yellowish-brown, flecked with cream and light orange-brown, usually with an orange-brown mark above shoulder of each rib. Protoconch breadth 0,85-0,95 mm, b/h 1,06-1,36. Attains about 19 mm.
Description: Shell claviform (b/l 0,38-0,44, a/l 0,33-0.35), apex narrowly papilliform (decollate in shallow-water examples), base short, truncate, teleoconch whorls about 6; suture shallow, each whorl clasping hitfh up the preceding one, shoulder angular, at or slightly above midwhorl. shoulder slope moderately concave, no distinct subsutural cord. left side of base of body whorl shallowly concave, fasciole strong, with a slight false umbilicus. Aperture oblong-ovate, greatest width median, columella almost straight, parietal region concave; siphonal canal wide, curved slightly to left, end weakly oblique to square-set, moderately notched; labial callus thick, edge slightly free over columella, forming a thick, laterally compressed pad posteriorly, which greatly constricts entrance to anal sinus; labrum gently convex in side-view, without distinct stromboid notch, anal sinus moderately deep, roundedly U-shaped, with greatly narrowed entrance, directed outwards or slightly abapically.
Sculptured by strong axial ribs, crossed by narrow spiral lirae; labrum preceded by a strong, rounded, often wide varix; growth-striae fine, but regular, rendering spiral grooves minutely pliculate. Axial ribs 8-9 on 1st whorl, 7-9 on penultimate and body whorls (including varix). slightly opisthocline, with rounded crests and gradually sloping sides, subequal to intervals, evanescing on shoulder slope, on body whorl reaching fasciole. Spiral lirae 6-7 on 1st whorl, 8-11 on penultimate whorl, usually absent above shoulder, but sometimes feeble striae on shoulder slope. 16-20 lirae on base (including rostrum).
Colour light yellowish-brown, flecked with white and brownish-orange to light orange-yellow, particularly below suture, and usually with a brown spot above shoulder of each rib, 1-2 shoulder lirae pale where cross axials, intervals between ribs and a spiral zone at parietal level tinged with light brown or yellowish-grey; apex usually moderate brown, occasionally light orange-yellow; aperture moderate brown to pale yellowish-pink.
Protoconch somewhat cylindrical and papilliform. of two whorls, smooth, except for faint axial riblets and about 6 feeble spiral threads terminally; breadth 0,85-0,95 mm. height 0,70-0,80 mm (b/h 1,06-1,36). Dimensions: 14,9 x 6,5 mm (holotype); largest paratype 18,5 mm (lip and protoconch broken); smallest adult paratype 11.6x5.0 mm; decollated paratype 17.1 x7,2 mm. Operculum as in rousi, but translucent deep yellowish-brown. Radula of about 45 rows of marginal plates.

The bathymetric range of N. scalpta is remarkable, and indicates it to be a subtropical species, living inshore in the warmer waters of Natal and Mozambique, but further south restricted to the outer continental shelf, which is under the influence of the warm Agulhas current. Littoral and shallow-water examples resemble typical Cape N. rousi in their decollated apex, only 3-4 teleoconch whorls being retained. Compared with rousi, axial ribs are fewer (7-9 on body whorl in scalpta. instead of 9-13), and stronger, with a more angular shoulder, spiral sculpture consists of thin, rounded lirae (instead of feeble grooves), whose intervals are crossed by fine axial striae (absent in rousi) and protoconch whorls are more rounded; the operculum of rousi is more orange in colour.

Southern Mozambique to East London (south-Africa), littoral (very rarely) to about 150 m.