Sixteen cheirurid trilobites are described from the Middle Ordovician Ogygiocaris and Chasmops series of the Oslo Region of Norway.
The genus Cyrtometopella, and also the species Paraceraurus helgoeyensis, Cyrtometopella tumula, C. askerensis, N ieszkowskia norvegica, H emisphaerocoryphe inflatus, and Atractopyge gracilis are new. The species Cybele brevicauda, C. coronata, C. dentata, C. kutorgae, C. revaliensis, C. rex, and C. woerthi are transferred to the genus Atractopyge. The species C. grewingki (Schmidt, 1881) is regarded as a synonym of Atractopyge dentata (Esmark, 1833). The species Hemisphaerocoryphe? rosenthali (Schmidt, 1881) is transferred to the genus Cyrtometopella n. gen.
A chart shows the stratigraphic occurrence of the described species.