Tivela trigonella (J.B.P.A. Lamarck, 1818)
Meroena trigonula (FOSSIL) (G.P. Deshayes, 1825 †)
Lioconcha trimaculata (J.B.P.A. Lamarck, 1818)
Lirophora trimeris (FOSSIL) Gardner, 1947 †
Katherinella trinitatis (FOSSIL) H.B. Stenzel & al.,1957 †
Tivela tripla (C. Linnaeus, 1758)
Pelecyora tripla (A. Römer, 1860)
Parastarte triquetra (T.A. Conrad, 1846)
Dosinia troscheli C.E. Lischke, 1873
Dosinia truncata Z. Zhuang, 1964
Sunetta truncata (G.P. Deshayes, 1853)
Dosinia tugaruana (FOSSIL) S. Nomura, 1935 †
Agriopoma tumbezana (FOSSIL) A.A. Olsson, 1932 †
Circe tumefacta G.B. II Sowerby, 1851
Circe tumefacta lenticularis G.P. Deshayes, 1853
Chione tumens Verrill, 1870
Pitar tumens (J.F. Gmelin, 1791)
Dosinia tumida (J.E. Gray, 1838)
Marama tumida (FOSSIL) (P. Marshall, 1918 †)
Costellipitar tumidus (G.B. III Sowerby, 1895)
Venus turgescens (FOSSIL) G.P. Deshayes, 1857 †
Dosinia turgida (L.A. Reeve, 1850)
Globivenus ucuttana (FOSSIL) (W.H. Dall, 1903 †)
Costacallista ugolnensis (FOSSIL) Devjatilova, 1981 †
Cyclinella ulloana L.G. Hertlein & A.M. Strong,1948
Panchione ulocyma (FOSSIL) (W.H. Dall, 1895 †)
Callista umbonella (J.B.P.A. Lamarck, 1818)
Meretrix undata (FOSSIL) (B. de Basterot, 1825 †)
Mysia undata (T. Pennant, 1777)
Chione undatella (G.B. I Sowerby, 1835)
Chione undatella neglecta (G.B. I Sowerby, 1835)
Chione undatella taberi C.F. Parker, 1949
Circe undatina (J.B.P.A. Lamarck, 1818)
Paphia undulata (I. von Born, 1778)
Meretrix undulifera (FOSSIL) A.E.M. Cossmann, 1906 †