Abstract
Twelve species of the diatom genus Thalassiosira, most of them recently described, are recorded from the Thames Estuary and other estuaries and places round the British coast. Brief notes, with transmission electron micrographs, are given on the following species: T. profunda (Hendey) Hasle, T. proschkinae Makarova, T. minima Gaarder emend. Hasle, T. tenera Proschkina-Lavrenko, T. decipiens (Grun.) J⊘rgensen, T. incerta Makarova, T. minuscula Krasske, and T. visurgis Hustedt. A table is given for the occurrence of these and of four other species among 12 collecting sites.