The described trilobite fauna occurs in beds immediately underlying the Upper Didymograptus Shale (Llanvim). A total of 34 species belonging to 21 genera are identified. The trilobites consist almost entirely of Baltoscandian types, but a faunal link to the trilobite fauna of the serpentine Otta Conglomerate
in central Norway, and to Western Newfoundland is documented. Five new species are described: Geragnostus hadros n.sp., Ogmosaphus tropidalox n. sp., Megistaspis (Heraspis) /aticauda n. sp., Megistaspis (Megistaspidella) giganteus n. sp., Megistaspis (Megistaspidel/a) maximus n. sp. Other recognised genera include: Carolinites, Telephina, Turgicephalus, Bronteopsis, Illaenus, cotoharpes, Cybelurus and Metopolichas as well as the species Asaphus (Neoasaphus) platyurus Angelin, 1854. The latter, in part, documents the presence of the boundary between the Olandian and Viruan Series (Lower and Middle
Ordovician) in the Oslo Region.