| Species | Name Used |
|---|---|
| Trichobranchus glacialis Malmgren, 1866 | Trichobranchus glacialis (p. 79 ) |
| Trichotropis bicarinata (Sowerby I, 1825) | Trichotropis bicarinata (p. 102 ) |
| Trichotropis insignis Middendorff, 1849 | Trichotropis insignis (p. 102 ) |
| Trididemnum tenerum (Verrill, 1871) | Trididemnum tenerum (p. 266 ) |
| Trochochaeta carica unspecified | Trochochaeta carica (p. 74 ) |
| Trochochaeta multisetosa unspecified | Trochochaeta multisetosa (p. 74 ) |
| Tubulanus albocinctus unspecified | Tubulanus albocinctus (p. 54 ) |
| Tubulanus annulatus (Montagu, 1804) | Tubularia annulatus (p. 54 ) |
| Tubularia indivisa Linnaeus, 1758 | Tubularia indivisa (p. 29 ) |
| Velutina plicatilis (Müller, 1776) | Velutella plicatilis (p. 103 ) |
| Velutina schneideri Friele, 1886 | Velutina schneideri (p. 104 ) |
| Velutina velutina (Müller, 1776) | Velutina velutina (p. 104 ) |
| Yoldiella tamara (Gorbunov, 1946) | Ledella tamara (p. 137 ) |