This survey describes the distribution of certain freshwater molluscs from the margins of the lowland canals of Scotland (Forth & Clyde Canal, Union Canal, and Monkland Canal). Fourteen species of gastropods and three species of
freshwater mussels were recorded. Of these species, Valvata cristata Müller 1774, Bithynia leachii (Sheppard 1823), Planorbis carinatus Müller 1774, Planorbarius corneus (L., 1758), and Acroloxus lacustris (L., 1758) were found to be much more widely distributed than previously reported. Although inconspicuous species such as A. lacustris and V. cristata may have been under-recorded in the past, the possibility is discussed that other species might have been spread during the recent restoration of the canals for navigation, and the consequent increased traffic and movement of water and vegetation. Other species previously recorded from the canals which were not found in this survey, such as Radix auricularia (L., 1758) and Dreissena polymorpha (Pallas, 1771), may have become extinct in the Scottish lowland canals, but would probably have been missed by the sampling methods used in this study.