Shell small, thin, fragile, colour violaceous with whitish band below the sutures, conically turbinate. Spire about half the length of shell. Whorls rounded, slightly obtusely angular about the middle. Sculptured with fine, somewhat irregular, oblique, radial striae. Interior light violet. Aperture somewhat ovate; outer lip very thin possessing a deep sharply angular sinus almost centrally situated; columella slightly reflected. Size: 0,5 inch.

Shell. In general like that of janthina but it has a taller spire, the whorls meeting slightly below the periphery of the upper one. The ornament is more marked, the growth lines elevated into distinct crests separated by deep grooves. On the last whorl they are V-shaped, changing direction from markedly prosocline to equally pronouncedly opisthocline at the periphery where there is often a shallow groove.
The protoconch is not so steeply tilted as in janthina and so is more exposed.
Aperture. Squarish. The outer lip arises from the peripheral groove of the last whorl and bears a deep V-shaped peripheral sinus. Its basal part is out-turned and curves sharply into the columella, the contact being nearly at right angles. The columella lies straight in the axis of the shell. The inner lip is thin and everted over a small umbilical groove.
Colour. A slightly darker violet than other species.
Size. Up to 17 x 14 mm. Last whorl = 80% of total shell height; aperture = 55-60% of shell height.
Animal, colour. As in janthina.

Distribution: Warm seas; Texas. Size: 6 mm.
Description: Color deep purple, except for white outline around edge of apertural lip; shape globose; sculpture smooth except for irregular, fine axial growth lines; whorls well defined and round; suture incised; body whorl broad, dominates shell; protoconch small, rounded, and slightly extended; aperture wide; outer lip with a distinct notch.
Habitat: Circumtropical; pelagic in warm seas.
Remarks: Has been misidentified as young J. globosa Swainson, 1822. See Abbott (1974); Andrews (1977).

Janthina exigua Lamarck, 1816. (Synonym: Janthina bifida Nuttall, Jay, 1839.) Height, 12 mm; diameter, 12 mm. Shell: globose; outer lip with a prominent notch; light violet. Spire: apex rather tall, whorls slightly flattened from above; suture distinct. Sculpture: regular, oblique, deep furrows slanting from the suture to the middle of the whorl, where they form a sinus. Aperture: outer lip distinctly notched. Color: light violet.
Shells in Hawaiian collections have been recorded only from the Leeward islands.

This is the smallest Violet Sea Snail in Victoria, easy to recognize by its radially sculptured whorls and deep angular sinus.