Occurrences of Psigraptus and Chigraptus gen. nov. in the Tremadoc of the Yukon Territory, Canada

The full stratigraphical context of the type materials of Psigraptus arctic us and II lenzi from Rod; River are given, as well as a new occurrence of t he Psigraptus-Adelograptus Zone in the Upper Canyon, Peel River of Canada's Yukon Territory. A new monotypic genus Chigraptus is created for a quadrir adiate anisograptid graptolite with four unbranched first-order stipes, a h orizontal to slightly reclined rhabdosome and isolate autothecae. The genus is found only at the base of the Early Tremadoc Anisograptus-Staurograptus Zone. Chigraptus may have given rise to the Late Tremadoc Psigraptus by a reduction in first-order stipes and by increased reclination.