Trochus anthracophilus (FOSSIL) F.A. Roemer, 1880 † Indonesia, Padang Highlands
Cantharidus antipodum (J.B. Hombron& C.H. Jacquinot, 1854) New Zealand, South Island5,1 mm
Oxystele antoni Herbert, 2015
Lirularia antoniae F. Rubio & E. Rolán, 1997 Gabon, Sao Tomé Island1,2 mm
Trochus apicalis (FOSSIL) Moore † UK, Wales
Parminolia apicina (A.A. Gould, 1862) New Caledonia, Loyalty Islands5,9 mm
Phasianotrochus apicinus (K.T. Menke, 1843) South Australia20,3 mm
Gibbula aquitanica (FOSSIL) A.E.M. Cossmann& M.A. Peyrot, 1917 † France, Aquitaine11 mm
Stomatella arabica A. Adams, 1854 Oman6,53 mm
Clanculopsis araonis (FOSSIL) (B. de Basterot, 1825 †) France, Aquitaine11 mm
Ozodochilus aratus (FOSSIL) Lycett † UK, England, Wiltshire
Trochus arcotensis E. Forbes, 1846
Gibbula ardens (C.U.A. von Salis-Marschlins, 1793) Turkey, Bozcaada Island13 mm
Gibbula ardens subcincta T.A. de M. Monterosato,1888 Tunisia, Gulf Gabes15 mm
Charisma arenacea (G.B. Pritchard& J.H. Gatliff, 1902) Tasmania
Diloma arida (H.J. Finlay, 1926) New Zealand, Auckland14 mm
Jujubinus armatus (FOSSIL) B.M. Landau, L. Ceulemans& F. Van Dingenen, 2016 † France, Loire
Clanculus aroanis (FOSSIL) (B. de Basterot, 1825 †) France, Aquitaine
Calthalotia arruensis (Watson, 1880) Queensland13,1 mm
Trochus artensis P. Fischer, 1878 New Caledonia
Pseudominolia articulata (A.A. Gould, 1861) South Africa, False Bay6 mm
Phorcus articulatus (J.B.P.A. Lamarck, 1822) Spain, Almeria17 mm
Clelandella artilesi C. Vilvens, F. Swinnen& F. Déniz, 2011 Western Sahara6 mm
Cantharidus artizona (A. Adams, 1853) New Zealand4,6 mm
Stomatella asperulata (A. Adams, 1850) Philippines, Siquijor2,9 mm
Trochus athenasi (FOSSIL) Vasseur, 1881 † France, Brittany
Stomatia atlantica F. Nordsieck, 1980 Portugal, Madeira
Phorcus atratus (W. Wood, 1828) Canary Islands20 mm
Phorcus atratus selvagensis F.F. Talavera, 1978 Canary Islands
Phorcus atratus trappei F. Nordsieck, 1982 Canary Islands17 mm
Clanculus atricatena J.R. le B. Tomlin, 1921 South Africa, Algoa Bay
Clanculus atropurpureus Gould, 1849 Singapore11,5 mm
Tosatrochus attenuatus (I.H. Jonas, 1844) Philippines, Aliguay Island24,2 mm
Trochus attrochus (FOSSIL) Hudleston † UK, Dorset
Clanculus atypicus (T. Iredale, 1912) New Zealand