Bay of Biscay to Canarias, Mediterranean; the species occurs in the deep circalittoral, the continental shelf and the slope (1450m, ‘Porcupine’ 1870; 1205m, ‘Travailleur’ 1881-1882 – Nobre, 1900). A depth of 2664m is mentioned off Algeria, without further explanations. Original taxon: Cioniscus gracilis.
 
The embryonal whorl shows two characteristic spiral keels. The teleoconch, of 4-5 whorls only, bears the usual undulating radials crossed by weak spirals. Above: a specimen dredged at 200m deep, off Dubrovnik, S. Croatia. 1,7mm. Original pictures provided by R. Stanić (HR) – (CC BY-NC-SA).

« Shell of nearly equal breadth throughout, thick, semitransparent, and glossy. Sculpture: numerous sharp and flexuous longitudinal ribs, which extend to the base; there are about 25 on the last whorl; each whorl is angulated or shouldered at the top; the first whorl and a half, which form the apex, are marked by two slight spiral striae, but are otherwise smooth and polished. Colour: whitish, with a faint tinge of yellowish-brown. Spire very gradually tapering to a blunt and apparently truncated point; apex somewhat inflected. Whorls 5½, convex, but rather compressed. Suture deep. Mouth somewhat more round than oval; peristome continuous or complete. Outer lip flexuous, usually strengthened by a rib, contracted above. Inner lip attached to the pillar, which is oblique; there is no umbilicus. » – Op. cit. p.341.

« This species is remarkable for its embryonic features. It has 2-3 whorls, globulous, smooth, wider than the rest of the shell, which is more spindly and adorned with flexuous costae. » – T. A. di Monterosato: “Recherches conchyliologiques, effectuées au Cap Santo Vito, en Sicile”, Journal de Conchyliologie vol. 22(3), Paris 1874, p.264. In fact, the embryonic whorls are not larger than those of the teleoconch, except, maybe, around the transition, where an optical ilusion could lead to believe that.