Shell medium-sized (10-45 mm), claviform (sometimes broadly so), often thick-shelled, base truncate; anal sinus U-shaped, usually rather shallow, not spout-like, stromboid notch shallow to deep; sculptured by strong axial ribs which do not reach the suture and which (typically) develop peripheral angles, nodules or even squamose spines; spiral lirae fine to feeble; usually vividly patterned with brown. Protoconch domed, of about 2 smooth whorls. Operculum oblanceolate, with terminal nucleus. Radula drilliine, rachidian small, unicuspidate (sometimes with tiny side-cusps), laterals arched, pectinate, marginals somewhat awl-shaped, with weak blade and accessory limb.

Shell small to medium, 6-30 mm, solid, high spired, truncated anterior end, often with thick shells. Protoconch paucispiral, 2 whorls, smooth, rounded. Teleoconch up to 8 whorls with axial sculpture including ribs or spines, spiral sculpture absent. Sinus wide, moderate depth, near suture. Callus strong. Outer lip thin, stromboid notch distinct Anterior canal broad, short, weakly notched- Colour white to light brown or grey, often with brown bands. Operculum oblolanceate, nucleus terminal. Tropical Indo-Pacific and Atlantic Oceans. Intertidal to 150 m.

Diagnosis. Shell claviform, adult length 6—45 mm, often thick, base truncate, not strongly slanted to right, with short, wide, shallowly notched siphonal canal. Inner lip with a heavy parietal pad, constricting opening to the shallow to deep, U-shaped anal sinus, but not rendering it spout-like; outer lip with a distinct stromboid notch. Sculpture of axial ribs or peripheral nodules, spiral sculpture only on base of last whorl or absent. Protoconch domed to papilliform, of approximately two (rarely three) smooth whorls. Operculum oblanceolate, with terminal nucleus.
Radula drilliine, central plate small, unicuspidate (sometimes with tiny side-cusps), laterals arched, pectinate, marginals somewhat awl-shaped, with weak blade and accessory limb.
Note. Tylotiella has been given full subgeneric or generic status by most authors (e.g. Powell 1966; Kilburn 1988; Poppe 2008), to include narrower species with a higher spire than in Clavus s.s., and axial ribs that extend over whole whorl height, and form neither spines nor angles. However, intermediate character states blur the dividing line, and we now prefer to regard Tylotiella as a synonym of Clavus.

The type species of Clavus, C. flammulatus, is aberrant in that it appears to retain somewhat immature apertural features as an adult. Within the genus there is a transformation sequence from the prominently spinose characterstate found in species such as canicularis (Roding, 1798), through those with sharp angles (eg exasperatus (Reeve, 1843), wilmeri (Smith, 1875)) to a state in which the shoulder bears only blunt tubercles (eg sikesi Preston. 1908, rugizonatus Mervier, 1895) or even sometimes none at all (unizonalis (Lamarck, 1822)). Some of the species listed under Clavus by Powell (1966) would be better placed in Tylotiella.