This volume is written by leading authorities in red algae. All subfamilies, genera and species are described, notes on ecology and distribution given, and each named species is illustrated by one or more half-tones or line drawings showing distinctive features. User-friendly keys are provided to enable identifi cation of genera and species. Special features of this volume are the concise but comprehensive and practical introduction and a complete re-evaluation of British Isles taxa in consultation with other international specialists. In addition, one new species and three new combinations are proposed.