Clithon teres T.C. Eichhorst, 2016
Nerita tessellata J.F. Gmelin, 1791
Septaria tessellata (J.B.P.A. Lamarck, 1816)
Neritoma tethys (FOSSIL) Morris 1949 †
Nerita textilis J.F. Gmelin, 1791
Neritina tiassalensis E.E. Binder, 1955
Theodoxus timisensis (FOSSIL) E. Jekelius, 1944 †
Theodoxus tingitana (P.M. Pallary, 1936)
Neritina tjidamarensis (FOSSIL) Martin, 1879 †
Theodoxus tortuosus (FOSSIL) E. Jekelius, 1944 †
Smaragdia tragena (T. Iredale, 1936)
Theodoxus transversalis (L. Pfeiffer, 1828)
Theliostyla triangulata (FOSSIL) W.M. Gabb, 1869 †
Nerita tricarinata (FOSSIL) J.B.P.A. Lamarck, 1804 †
Nerita tricarinata pentastoma (FOSSIL) G.P. Deshayes, 1864 †
Theodoxus trifasciatus (FOSSIL) (J.P.S. Grateloup,1839 †)
Theodoxus trilophosensis (FOSSIL) Rust, 1997 †
Nerita tristis H.A. Pilsbry, 1901
Clithon tritonensis (E.J. Le Guillou, 1841)
Theodoxus tropidophorus (FOSSIL) (Š. Brusina, 1884 †)
Cuisenerita tuberosa (FOSSIL) Symonds & J.M. Pacaud,2010 †
Theodoxus turbinatus (FOSSIL) (A. Fuchs, 1870 †)
Theodoxus turislavicus (FOSSIL) E. Jekelius, 1944 †
Neritina turrita (J.F. Gmelin, 1791)
Neritina turrita cumingiana C.A. Récluz
Vittina turtoni (C.A. Récluz, 1843)
Nerita umlaasiana (C.F.F. von Krauss, 1848)
Nerita undata C. Linnaeus, 1758
Nerita undata spengleriana C.A. Récluz, 1844
Nerita undulata J.F. Gmelin, 1791
Theodoxus unguiculatus (FOSSIL) (Seninski, 1905 †)
Neritina unidenta (FOSSIL) T.H. Aldrich, 1911 †
Neritina unidentata C.A. Récluz, 1850
Neritina usnea (P.F. Röding, 1798)
Neritina usnea reclivata T. Say, 1822