Agardhiella subulata (C.Agardh) Kraft & M.J.Wynne, 1979 (additional source)
Anguillicola crassus Kuwahara, Niimi & Itagaki, 1974 (additional source)
Antithamnionella spirographidis (Schiffner) E.M.Wollaston, 1968 (additional source)
Antithamnionella ternifolia (Hooker f. & Harvey) Lyle, 1922 (additional source)
Bonnemaisonia hamifera Hariot, 1891 (additional source)
Clavopsella navis (Millard, 1959) accepted as Pachycordyle michaeli (Berrill, 1948) (additional source)
Clymenella torquata (Leidy, 1855) (additional source)
Codium fragile subsp. atlanticum (A.D.Cotton) P.C.Silva, 1955 (additional source)
Codium fragile subsp. tomentosoides (van Goor) P.C.Silva, 1955 accepted as Codium fragile subsp. fragile (Suringar) Hariot, 1889 (additional source)
Colpomenia peregrina Sauvageau, 1927 (additional source)
Gonionemus vertens A. Agassiz, 1862 (additional source)
Grateloupia doryphora (Montagne) M.Howe, 1914 (additional source)
Grateloupia filicina var. luxurians A.Gepp & E.S.Gepp, 1906 accepted as Grateloupia subpectinata Holmes, 1912 (additional source)
Haliplanella lineata (Verrill, 1869) accepted as Diadumene lineata (Verrill, 1869) (additional source)
Hydroides dianthus (Verrill, 1873) (additional source)
Marenzelleria viridis (Verrill, 1873) (additional source)
Odontella sinensis (Greville) Grunow, 1884 accepted as Biddulphia sinensis Greville, 1866 (additional source)
Pikea californica Harvey, 1853 (additional source)
Pleurosigma simonsenii Hasle, 1990 (additional source)
Polysiphonia harveyi Bailey, 1848 accepted as Melanothamnus harveyi (Bailey) Díaz-Tapia & Maggs, 2017 (additional source)
Solieria chordalis (C.Agardh) J.Agardh, 1842 (additional source)
Thalassiosira punctigera (Castracane) Hasle, 1983 accepted as Ethmodiscus punctiger Castracane, 1886 (additional source)
Thalassiosira tealata Takano, 1980 (additional source)
Undaria pinnatifida (Harvey) Suringar, 1873 (additional source)

English common cord-grass [from synonym] for Spartina townsendii var. anglica (C.E. Hubbard)