The silurian ostracoda of the Oslo region, Norway. PollicottPaul D. 2015 A study of the ostracode fauna from the Silurian of Norway has been undertaken. All of the taxa recoverd and described are from the Llandovery and Wenlock Series; one species from the topmost part of the Ordovician of the Oslo region is also figured. Research has concentrated particularly upon the Palaeocopa Henningsmoen, 1954, but also includes the Leperditicopida Scott, 1961. The 'non-palaeocopes', because of particular problems related to preservation and taxonomy, are not treated as extensively. Primary revision has been made wherever possible. Such work has been augmented by studies of extensive new collections made from throughout the Oslo region, particularly from the Ringerike, Oslo-Asker and Holmestrand districts. This study has concentrated firstly on the taxonomy of the fauna. There are chapters on the Leperditicopa, Palaeocopa and 'non-palaeocopes'. Other chapters deal with the palaeoecology, biostratigraphy and correlation and affinities of the fauna. A full faunal and associated locality list, together with information on regional stratigraphy, is also presented. The fauna is 26 genera (2 new), 43 named species (14 new) and 15 other forms are described under open nomenclature. The Silurian ostracode fauna of Norway is mostly endemic (at specific level) but does have affinities with Gotland, Siberia and Britain. Ostracode potential for correlation between various districts of the Oslo region is best realised in the Steinsfjorden Formation. Standard micropalaeontological techniques have been used throughout, with most material being prepared by 'Vibrotool', and photographed on the Scanning Electron Microscope.