Abstract The writer has grouped the graptolite fauna of the Canajoharie-Utica (and Macasty) shale of the St. Lawrence Lowlands and Anticosti Island into four zonal assemblages, thus simplifying the zonation proposed by Ruedemann for these units. The Canajoharie is herein restricted to comprise only the lower and middle Canajoharie of Ruedemann, or the two lower zones of this paper. The upper Canajoharie is included in the Utica because its fauna is practically indistinguishable from that of the lower half of the Utica (of Ruedemann). A distinct change in fauna separates the Utica from the Canajoharie. The Utica fauna consists of two broad and overlapping assemblages with many forms in common. The disappearance of this fauna with the end of Utica deposition is thought to mark a reliable boundary between middle and upper Ordovician for the grap-tolite-bearing strata of northeastern North America. The Lorraine Group of the St. Lawrence Lowlands and the English Head, Vaureal, and Ellis Bay Formations of Anticosti contain three additional graptolite assemblages. Ashgillian graptolites range through the middle and upper English Head; the succeeding Vaureal and Ellis Bay of Richmondian and Gamachian ages yield a hitherto unknown post-Ashgillian but pre-Silurian graptolite fau-nule. Thus it is apparent that (1) the Richmondian no longer can be considered correlative with strata bearing Ashgillian graptolites, and (2) the known standard graptolite successions are incomplete with respect to the Anticosti succession. In the Mohawk Valley of New York, the Canajoharie Shale (of this paper) is correlative with the Denmark (upper Sherman Fall) limestone,