DISTRIBUTION. — Distorsio anus is very widespread in shallow water throughout the Indo-West Pacific province, from Natal. South Africa, throughout the Indian Ocean to Somalia and southern India, and in the Red Sea (although I have seen no records from the Gulf of Arabia); in the western Pacific it occurs as far north as the Kii Peninsula. Honshu. Japan (OYAMA & TAKEMURA. 1959: Distorsio pl. 2. fig. 5) and as far south as Queensland. Australia, and New Caledonia; and as far east as Hawaii (KAY. 1979) and Pitcairn (1, KMNZ M270993. coll. P. Sharpies. 1994).

DIMENSIONS. — Murex anus(lectotype): H 51.0, D 36.7.

REMARKS. — Distorsio anus is one of the most distinctive of all molluscs and being reasonably common, has been listed and illustrated in so many papers, monographs and popular hooks it would be pointless to list them all. The synonymy above includes the synonyms, most of the early, well-known iconographies, some modem papers (e.g. CERNOHORSKY. 1967a: 323; radula described and illustrated) and several popular books where it has been illustrated in colour. The most distinctive characters are its extremely distorted coiling, the dark red-brown and white spiral banding of the teleoconch exterior, the anterior canal being bent low.irds the dorsum at right angles to the plane of the aperture, and the extraordinarily developed apertural shield, highly polished but bearing numerous, irregular nodules and hollows (as the previous whorls show through), hiding much of the rest of the shell (apart from the spire apex) in ventral view in large specimens. The interior of the outer lip bears the usual Distorsio row of large nodules, the third from the adapical end much the largest, and the columellar base bears the usual Distorsio prominent ridge protruding to the right into the aperture, bearing prominent, thin, transverse ridges - in this species, five or, less commonly, six ridges. Man> specimens have alternate white and red-brown radiating colour splashes around the outer margin of the apertural shield. Juvenile specimens have a narrowly conical, undistorted spire.
As Distorsio anus is the sole species of the genus occurring commonly in shallow water (even occasionally found intertidally on sand fiats) throughout the Indo-West Pacific province, it is not surprising that several specimens are present in the LAGON and EXPEDITION MONTROUZIER samples and in samples from the Coral Sea. However. D. anus appears to be relatively uncommon in New Caledonia.

Distorsio anus (Linnaeus, 1758). Length, 66mm; diameter, 33 mm. Shell: distorted, swollen, knobby; aperture denticulate, parietal shield covering preceding two whorls; white and brown. Spire: protoconch of three bulbous, white whorls; teleoconch short, distorted, whorls inflated and convex: suture at varying angles. Sculpture: spiral cords crossed by axial ribs, forming a nodular network over the surface of the shell, parietal shield with numerous axial cords. Aperture: small, distorted, ovate; parietal shield oval to round with deep ruffles around the perimeter, covering the preceding two whorls; outer lip denticulate, teeth jutting into the aperture and considerably condensing it; anterior canal angled and curved; siphonal canal long and recurved. Color: white, banded with red-brown; parietal shield white to diffused orange-tan. These tritons are uncommon, found at depths of 10 m and more. They live in small sand pockets on hard substrates or under coral slabs (Burgess, 1963). Elsewhere in its range D. anus occurs in shallow water: in the Cocos-Keeling Islands Abbott (1950) recorded it from a depth of 3.6 m; in northern Australia it is found under stones on coral reefs (Allan, 1950), and in Fiji "under coral rocks on coral substrate, in shallow water" (Cernohorsky, 1967a).