Shell. This looks like a small and slightly stumpy specimen of Colus sabini, with which, indeed, it has often been confused. It has 7-8 swollen whorls and deep sutures which usually lie less obliquely than those of C. sabini. The spire has a blunt tip and its profile is only slightly, if at all cyrtoconoid. The ornament is as in that species though the alternation of larger and smaller spiral ridges is cither not clear or is absent; the periostracum is more obvious and shows a tendency to be more hairy along the spiral ridges. The initial whorl of the protoconch is smooth and a little insunk, the next marked with several spiral ridges.
Aperture. A broad oval, connecting widely with the siphonal canal at its base. The outer lip originates below the periphery of the last whorl and curves smoothly to the base, usually inflected where it joins the canal, which though still short, is commonly relatively longer than in sabini. The columella thus also appears longer than in that species. The parietal lip is narrower than in C. sabini and docs not thicken in the same way.
Colour. The shell is white, the pcriostracum brown with a greenish tint. Size. Up to about 40 x 25 mm. Last whorl = 70-75% of total shell height; aperture = c. 55% of total height; canal = c. 10% of total height. Animal. As in T. fenestratus. The operculum is triangular rather than oval with an apical nucleus. Colour. White-cream.
Geographical distribution. This is a northern species found off Iceland and the Faroes, along the Norwegian coast, and extending into the Skagerrak. It does not occur nearer the British Isles than the area between the Hebrides and Shetlands to the south and the Faroes to the north.
Habitat. On soft bottoms from 200 to 1000 m deep.
Food, breeding and growth. Unknown for certain, but probably as in T. fenestratus and Colus spp.