T. E. Thompson and Gregory H. Brown: British Opisthobranch Molluses. Mollusca: Gastropoda. Keys and Notes for the Identification of the Species. Synopses of the British Fauna No. 8 by the Linnean Society of London. With 105 figs., 203 pp. – London, New York and San Francisco: Academic Press 1976. ISBN 0‐12‐689350‐0 £ 3,50