Abstract
Observations are reported on the occurrence of Skeletonema subsalsum (Cleve-Euler) Bethge in Lough Erne, a eutrophic freshwater Irish lake. The diatom forms a summer maximum. Observations of the silica content suggests it is very lightly silicified and probably has the lowest silica content of any freshwater diatom so far reported. An account is given of cell structure under LM and SEM.