23 TWO NEW IDENTIFICATION GUIDES Provisional Keys to British Plant Galls Edited by F. B. Stubbs Published by The British Plant Gall Society £4.5D including postage All orders and enquiries to:— Mr. F. B. Stubbs 27 Annasgarth, Harmby Leyburn, North Yorkshire, DL8 5PJ. This guide is the only one presently available to help identify these organisms. It is based on the plant the gall is formed on and is illustrated with line drawings. Excellent value for any naturalist. Introduction to Freshwater Algae by Allan Pentecost Published by Richmond Publishing Co. Ltd., Orchard Road, Richmond, Surrey. £11.95 A much needed set of keys to genera with descriptions of common species and good line illustrations. An essential aid to any owner of a microscope who wishes to gain an insight into a much neglected group. TONY BONIFACE