The trilobite genera Panarchaeogonus Öpik, Isbergia Warburg and Cyamops gen. nov. from the Ordovician of Balto-Scandia and British Isles

Panarchaeogonus, hitherto classified with either Olenidae, Brachymetopidae, or Otarionidae [=Aulacopleuridae], is here included in the last-named, and together with lsbergia and Cyamops gen. nov. is placed in the Scharyiinae. Previously known species are described, together with Panarchaeogonus ph/yzacius sp. nov. and Cyamops stensioei gen. et sp. nov. Additional species of Panarchaeogonus and Cyamops are described under open nomenclature.