| Thaisella Clench, 1947 |
| Thaisella kiosquiformis (Duclos, 1832) |
| Trachypollia Woodring, 1928 |
| Trachypollia lugubris (C. B. Adams, 1852) |
| Trachypollia nodulosa (C. B. Adams, 1845) |
| Trachypollia sclera Woodring, 1928 |
| Trachypollia turricula (Maltzan, 1884) |
| Trialatella Berry, 1964 |
| Trialatella cunninghamae Berry, 1964 |
| Tribulus H. Adams & A. Adams, 1853 |
| Tribulus planospira (Lamarck, 1822) |
| Tripterotyphinae d’Attilio & Hertz, 1988 |
| Tripterotyphis Pilsbry & Lowe, 1932 |
| Tritonalia Fleming, 1847 |
| Tritonalia (Ocinebrina) Jousseaume, 1880 |
| Tritonalia (Ocinebrina) caribbaea Bartsch & Rehder, 1939 |
| Trophon Montfort, 1810 |
| Trophon aculeatus Watson, 1882 |
| Trophon cerrosensis Dall, 1891 |
| Trophon lacunellus Dall, 1889 |