Protoconch 2 smooth shining whorls, merging gradually into main whorls, nucleus slightly submerged. Teleoconch 5 whorls, first 3 almost flat, penultimate and body-whorl convex, strongly shouldered and becoming increasingly canaliculate with age. Sutures well impressed, at base of deep canal. Sculpture 12-14 sharp and very oblique ribs, forming prominent sharp scaly projections on shoulders, inclined to right, continued across canal to sutures as sharp oblique ridges; ribs crossed by about 15 sharply raised transverse striae on body-whorl, 8 on pen¬ultimate; ribs cross into umbilical opening as sharp raised striae; ribs consist of lamellations, mostly in pairs, but often up to 8, densely packed in 2 or 3 places including outer-lip, as maturity is reached. Umbilicus broad and deep, with inner-lip of aperture strongly reflected over the opening. Aperture subtrigonal, tapering anteriorly to a narrow open siphonal canal, reflected towards outer-lip; peritreme entire; very small tooth posteriorly; outer-lip heavily thickened, slightly reflected and sharply-edged, 11-12 lirae within; columella curved to right, plaits 3, evenly spaced, all slightly oblique. Colour white with dark brown band below shoulders, not showing on ribs, wide pale brown band below this then narrow white band, followed by thin red-brown line; dark brown patches deep in aperture. Dimensions. Holotype, length 15-8 mm. Maximum dimensions approx. 22 mm x 16 mm.

This species has been regarded by some workers in the past as a synonym of Cancellaria scalarina Lamarck, however examination of a number of specimens of each species from numerous localities shows them to be distinct. T. lamellosa has a lower spire, with body-whorl averaging 85 per cent of total length, compared with 78 per cent in T. scalarina, which species also has the umbilicus decidedly closer to the anterior end of shell. The axial ribs in T. lamellosa, also the columella, are more oblique, the ribs are composed of 2 or 3 lamellations, closely packed but quite distinct with sharp edges, which also applies to the recurved scaly projections on top of shoulders; the numerous densely packed lamellae forming the mature outer-lip are also separated to a certain extent, and not firmly fused together and glazed over as in T. scalarina, presenting in that species a much more solid appearance.

Distribution. 32 km N. of Delambre Island, Dampier Archipelago, Western Australia (20° 27' S., 117° 05' E.), southwards to S.E. corner of Dirk Hartog Island, W. Aust. (26° 05' S., 113° 15' E.).
Type locality. "Indian Archipelago". (Possibly intended to mean Lacadive Islands-Maldive Islands groups).