Article: Caradocian bivalve molluscs from Wales

The occurrence of a widespread, distinctive, and sometimes well-preserved bivalve fauna from the Lower Longvillian (Ordovician, Caradoc) rocks of North Wales is recorded, especially from the Allt-Tair-ffynon Beds at Allt y Gadair, south of Llanfyllin, Powys. Six species are described, of which Cymatonota verisimilis sp. nov., Myodakryotus deigryn gen. et sp. nov., and Pseudarca celtica sp. nov. are new. The new family Myodakryotidae is established to accommodate the new genus Myodakryotus.