The graptolite fauna of the Dictyonema Shales of the Oslo region

This is the first attempt at a complete revision of the graptolite fauna of the Dictyonema Shales (Ze) of the Oslo district. Two localities have been selected, Tøyen and Hammersborg; the former provides a practically complete succession, and the latter has furnished a remarkably rich A nisograptus fauna in its upper portion. The presence of anisograpticls as a characteristic component of the fauna, and the absence (or extreme rarity) of Clonograptus, seems to link the Norwegian succession with the Dictyonema Shales of eastern North Aæerica. Variation in Dictyonema flabelliforme and the stratigraphical value of its varieties are discussecl; and the systematic section comprises descriptions of eighteen forms (Dictyonema and Anisograptidae) including three new species and three new varietles.