This book presents a wide-ranging introduction to the diatoms together with an illustrated description of over 250 genera. Diatoms are important as perhaps the commonest group of autotrophic plants on earth and are abundant in all waters and on soils and moist surfaces. The introduction describes the diatom cell in detail, the structure of the wall (often extremely beautiful in design), the cell contents and aspects of life cycle and cell division. The generic atlas section is the first account of diatom systematics since 1928 (Karsten in Engler and Prantl: Die Nauturlichen Pflanzenfamilien) and each generic description is accompanied by scanning electron micrographs to show the characteristic structure. Most of the latter have been prepared specially for this work from the authors' own collections. The Diatoms will be the standard reference work on the group for years to come and is an essential reference volume.

This book is based on a workshop on biogeography of freshwater algae held during the Fifth International Phycological Congress in China 1994. A group of outstanding specialists covering widely different approaches to the subject have been brought together, and this collection of their contributions forms a unique volume: there is no other book on the subject. It thus fills an evident gap in the phycological literature, and will be of major interest to researchers and teachers within phycology, limnology, and evolutionary biology. However, it may also be useful in courses for advanced students.

Scotland is fortunate in being very richly endowed with natural fresh waters in the form of numerous lochs and rivers. These constitute on the one hand an attractive feature of the landscape and on the other a major resource for industry and recreation. Thus there are about 3800 lochs over4 ha in area and these form approximately 1.0% of the total surface area of Scotland. Com parable figures for England and Wales are 1700 lakes and 0.05% of the land surface, and in terms of volume. Loch Ness contains more water than all the lakes and reservoirs in England and Wales put together (Smith & Lyle 1979). Many of the Scottish lochs are large and clean and consequently are particularly valuable in resource terms. The decision as to which are actually the largest lochs is debatable, particularly when the main criteria of greatest surface area, length, volume and depth each gives a different water (Lochs Lomond. Awe, Ness and Morar respectively). These four then are certainly among the largest lochs in the country, but close to them in size come several other large waters, among which is Loch Shiel- which is exceeded in length only by Lochs Awe, Ness and Lomond. These five very large lochs (Frontis piece) form the group of waters selected for the comparative studies described in this volume.