Sediment filled fissures are common within Middle and Upper Ordovician carbonate mounds in the Siljan district, Dalarna, central Sweden. The fossil content of a fissure in the Upper Ordovician Boda Limestone at Solberga indicates at late Ashgill (Hirnantian) and Llandovery age. The Ashgill fillings consist mainly of carbonates and mudstoncs, whereas the Llandovery sediments are black graptolitic shales. Seven species of Bryozoa occur commonly. These species also occur in the Öjle Myr Beds and are consequently of late Ashgill age. Three new species,Phaenopora wimani, Stictoporella siljanensisandFistulipora gustaviare described.