The exceptionally preserved crustacean fauna from the Upper Carboniferous of the Leinster Coalfield is described in this richly illustrated special paper. The abundant conchostracan genus Limnestheria is dealt with in considerable detail, including discussions of its affinities and classification. Other taxa include Waterstonella and ostracods. This work on a little-known fossil Konservat-Lagerstutte should be an important addition to the library of any worker on fossil arthropods.