Note su alcune specie fossili di Williamia (Gastropoda:Siphonariidae) con descrizione di una nuova specie

This paper focuses on some specimens of Williamia from Pliocene outcrops in Liguria and Tuscany (NorthernItaly). From this material, two species were identified, one of which is described as Williamia plioligustica n. sp. It has a large, globose protoconch, well distinct from that of the other living and fossil speciesknown for the genus. The other species, here referred to as Williamia sp., is based on a single specimen similar to the living Mediterranean species Williamia gussonii (O.G. Costa, 1829), but with a notably higher apex and a roundish apertural outline. The type material of W. gussonii var. pliocenica Sacco, 1897 and var. miocenica Sacco, 1897, used for comparisons with the new species, is here illustrated.