if, in C. vulgatum, spiral cords are of two different types (cf. left detail), in C. protractum they are of equal width. This shell has an alternance of large and thin cords, and shows, also, in the large cords only, an alternance of strong and weak ones. Above: possibly downslope transported specimen of vulgatum, collected at 400m deep, in muddy grit, off Civitavecchia, Lazio, W. Italy. 37mm. This morph, remarkably turreted, with numerous strong varices and a marked suture, seems to inhabit in deeper water than the usual form.

The taxon is considered as a synonym of vulgatum on MolluscaBase, with the following note: « This name has been extensively used by European authors, following the lead of Bucquoy, Dautzenberg & Dollfus, 1883, for the species correctly identified as Cerithium lividulum Risso, 1826. The type specimen in Risso’s collection, unavailable at the time of B.D.D., is a stunted form of C. vulgatum. »

In contrast to the large specimens of vulgatum, this small group inhabits the shallow rocky areas, together with lividulum. One difference with the latter is the absence of crisscrossed sculpture, which often gives rise to buttons. Here, this is replaced by spiral striae and well individualized nodules, especially under the suture, like in the vast majority of the larger specimens of vulgatum.