Covers the 31 different species of freshwater bivalves known in Britain and Ireland. Identification is aided by easy-to-follow illustrations and comparative tables that emphasise key features. Field identification of large mussels is possible using external features of live specimens. Individual species accounts are included, which provide more detailed information on distribution, small-scale habitat requirements, diagnostic and variable features, conservation status and notes on how the species may be separated from similar species. The guide contains numerous colour illustrations of all species.