Shell medium size for the genus, narrow, elongate fusiform; spire high with moderately convexed sides: protoconch small, blunt, dome shaped, smooth, of about 3 whorls; whorls including protoconch about 14 to 15 in number: aperture oblong, with smooth lip: outer lip expanded on its middle, producing shallow stromboid notch; inner lip covered narrow callus, of which posterior portion has a weak nodule narrowing posterior notch.
Axial sculpture sharp and narrow, and started from the first post nuclear whorl; axials apart each other about twice of its breadth and become obsolete at base and shoulder slope of later whorls; fine, curved growth lines densely carved on shoulder space, reflecting scars of posterior sinus; spirals lack in earlier several whorls, then crossed with axials. producing granulations; it numbers 4 to 5 on penultimate whorl; minute spiral striae densely covered on shoulder space and inter spaces of primary spirals. Localities and measurements of the present material: Shell height 43 to 46 mm, width 12,5 to 14 mm.

Shell: Shell large for genus, up to 58 mm, light, narrow, very high spire. Protoconch worn and eroded in Western Australian material. Up to 12 convex teleoconch whorls. Suture narrow, distinct, nearly straight, slightly channeled. Sculpture complex, dominated by strong, narrow axial ribs, 16 on penultimate whorl, begin below suture cord, rapidly expand to reach rounded peak at midwhorl, decrease but reach lower suture, 15 on body whorl, extend well beyond shoulder but not to anterior tip of shell, penultimate rib swollen into strong varix. Numerous strong axial striae below cord, 8 on penultimate whorl, about 24 on body whorl. Outer lip thin, strongly incurved with broad, indistinct, shallow stromboid notch. Sinus subsutural, at 45° angle to shell axis, very deep, moderate width, U shaped, margins callused, entrance slightly constricted by outer lip and strong low subsutural callus. Aperture elongate, narrow, subrectangular. Columella narrow, smooth, slightly convex, margin calluscd. Shell truncate, anterior canal short, narrow, deep, anterior tip slightly notched and raised. Shell colour indeterminate in Western Australian material, heavily eroded light gray.

The Western Australian specimens of Inquisitor angustus were identified and figured by Kosuge (1992), and the identification is based on Kosuge's analysis. The material represents a considerable range extension from the type locality in Japan.
Inquisitor angustus is part of a suite of Inquisitor species that are very similar in appearance. Other species included in the group arc I. jeffreysi (Smith, 1875) and I. nudivaricosus Kuroda and Oyama, 1971 and Ptychobela flavidula (Lamarck, 1816). The radula of I. angustus has not been figured, but when it is whether the species belongs in Inquisitor or Ptychobela will be clear. Inquisitor angustus is of the same size as the other three species but has a narrower shell, higher spire, and weaker axial ribbing.

North Western coast of Australia, Philippines to Japan (Sagami Bay)

Type locality: 70-80 m depth, Barane, Sagami Bay, Japan. Material examined: 200 m depth, 210 km N of Port Hedland. Western Australia (18"25'S; 118°22'E). Distribution: Japan to northwestern Australia.