Volvulella acuminata (Bruguière, 1792)
Norway to Angola, Mediterranean.
Predator on mobile preys in the infralittoral-circalittoral sedimentary botttoms. Original taxon: Bulla acuminata.
Above and below: on sand-dune among gramineous, Le Cavaou, Fos-sur-Mer, Bouches-du-Rhône, S. France. 1,7mm.
It is not stated yet wether the genus Rhizorus Montfort 1810 is a senior synonym of Volvulella Newton 1891. Both are described after empty shells, and are therefore based on conchological characters only.
 
Rhizorus: « Shell free, univalve; spire rolled on itself; apex recessed, umbilicate; aperture longer than the body of the shell, entire; outer lip higher than the top, sharp. » – P. Montfort: Conchyliologie systématique et classification méthodique des coquilles vol. II, Paris 1810, p.339, after a shell found in Italy.
Above and below: 80m deep, Hvar channel, Split-Dalmatia Comitat, S. Croatia. 3,85mm. Notice how the posterior extremity, badly damaged, underwent significant repairs.
Volvulella: named after Volvula A. Adams in G. B. Sowerby, Thesaurus conchyliorum vol. II, London 1855, p.558. Adams gives the following description: « Shell subcylindrical, beaked at both ends; spire concealed; aperture narrow; inner lip with a single obsolete fold. »

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