''Semicassis'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of medium-sized predatory

sea snail Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguishe ...

s, marine

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

s in the subfamily

Cassinae The Cassidae are a Taxonomy (biology), taxonomic family (biology), family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine (ocean), marine gastropod mollusks in the super ...

within the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Cassidae The Cassidae are a taxonomic family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine gastropod mollusks in the superfamily Tonnoidea and the clade Littorinimorpha.Gofas ...

, the helmet snails and bonnet snails.WoRMS : Semicassis; accessed: 30 July 2020
/ref>

Species

According to the

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scien ...

(WoRMS), the following species with valid names are included within the genus ''Semicassis'': *'' Semicassis adcocki'' (Sowerby III, 1896) *'' Semicassis angasi'' (Iredale, 1927) *'' Semicassis bisulcata'' (Schubert & Wagner, 1829) *'' Semicassis bondarevi'' Mühlhäusser & Parth, 1993 *'' Semicassis bulla'' Habe, 1961 *'' Semicassis canaliculata'' (Bruguière, 1792) * '' Semicassis cancellata'' (Lamarck, 1803) *'' Semicassis centiquadrata'' (Valenciennes, 1832) *'' Semicassis craticulata'' (Euthyme, 1885) * '' Semicassis decipiens'' (Kilburn, 1980) * '' Semicassis dorae'' (Kreipl & Mühlhäusser, 1996) * '' Semicassis dougthorni'' Dekkers, 2013 *'' Semicassis faurotis'' (Jousseaume, 1888) * '' Semicassis fernandesi'' (Kilburn, 1975) * † '' Semicassis fibrata'' (P. Marshall & Murdoch, 1920) *'' Semicassis glabrata'' (Dunker, 1852) *'' Semicassis granulata'' (Born, 1778) - synonym: ''Phalium granulatum'' (Born, 1778) * † '' Semicassis grateloupi'' (Deshayes, 1853) *'' Semicassis inornata'' (Pilsbry, 1895) * † '' Semicassis kaawaensis'' (Bartrum & Powell, 1928) *'' Semicassis labiata'' (Perry, 1811) * † '' Semicassis laevigata'' (Defrance, 1817) * †'' Semicassis lilliei'' (C. A. Fleming, 1943) * † '' Semicassis marwicki'' (C. A. Fleming, 1943) *'' Semicassis microstoma'' (Martens, 1903) * † '' Semicassis neumayri'' (Hoernes, 1875) *'' Semicassis paucirugis'' (Menke, 1843) *'' Semicassis pyrum'' (Lamarck, 1822) *'' Semicassis royana'' (Iredale, 1914) *'' Semicassis saburon'' (Bruguière, 1792) *'' Semicassis semigranosa'' (Lamarck, 1822) *'' Semicassis sinuosa'' (Verco, 1904) * † '' Semicassis skinneri'' (Marwick, 1928) *'' Semicassis sophia'' (Brazier, 1872) * † '' Semicassis subsulcosa'' (Hoernes & Auinger, 1884) * † '' Semicassis szilviae'' Kovács & Vicián, 2018 *'' Semicassis thachi'' Kreipl, Alf & Eggeling, 2006 *'' Semicassis thomsoni'' (Brazier, 1875) *'' Semicassis umbilicata'' (Pease, 1861) * '' Semicassis undulata'' (Gmelin, 1791) *'' Semicassis westralis'' Kreipl, 1997 *'' Semicassis whitworthi'' (Abbott, 1968) * '' Semicassis zeylanica'' (Lamarck, 1822) ;Species brought into synonymy: * ''Semicassis cicatricosa'' (Gmelin, 1791): synonym of '' Semicassis granulata'' (Born, 1778) * ''Semicassis diuturna'' Iredale, 1927: synonym of ''Semicassis bisulcata'' (Schubert & J. A. Wagner, 1829) * ''Semicassis japonica'' (Reeve, 1848): synonym of ''Semicassis bisulcata'' (Schubert & J. A. Wagner, 1829) * ''Semicassis miolaevigata'' Sacco, 1890: synonym of ''Semicassis saburon'' (Bruguière, 1792) * ''Semicassis obscura'' Habe, 1961: synonym of ''Semicassis bulla'' Habe, 1961 * ''Semicassis pauciruge'': synonym of ''Semicassis paucirugis'' (Menke, 1843) * ''Semicassis persimilis'' Kira, 1955: synonym of ''Semicassis bisulcata'' (Schubert & J. A. Wagner, 1829) * ''Semicassis pila'' (Reeve, 1848): synonym of ''Semicassis bisulcata'' (Schubert & J. A. Wagner, 1829) * ''Semicassis salmonea'' Beu, Bouchet & Tröndlé, 2012: synonym of '' Semicassis bulla'' Habe, 1961

Extinct Species

Extinct species within this genus include:Fossilworks
/ref> *''Semicassis aldrichi'' Dall 1890 † *''Semicassis angasi'' Iredale 1927 † *''Semicassis deneseplicata'' Martin 1916 † *''Semicassis harpaeformis'' Lamarck 1803 † *''Semicassis labiata'' Perry 1811 † *''Semicassis monilifera'' Sowerby 1846 † *''Semicassis oligocalantica'' Vredenburg 1925 † *''Semicassis ovulum'' Ortmann 1900 † *''Semicassis pyshtensis'' Addicott 1976 † *''Semicassis reclusa'' Guppy 1873 † Fossils of species within this genus have been found all over the world in sediments from

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

(age range: 37.2 to 0.0 million years ago).

References

* Powell A. W. B. (1979). William Collins Publishers Ltd, Auckland . Cassidae Gastropod genera Extant Eocene first appearances {{Cassidae-stub