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 farms in common. The disappearance of this fauna with the end of Utica deposition is thought to mark a rel able boundary between middle and upper Ordovician for the graptolite-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 faunule. 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, and the lower Utica is apparently coeval with part of the lower Cobourg; upper Utica strata lie disconformably on the lower Cobourg. In the St. Lawrence Lowlands, upper Canajoharie graptolites are present in limestone units that are homotaxial with the lower Cobourg of New York; lower Utica graptolites have been recovered in upper Cobourg beds. In the subsurface of Anticosti, lower Canajoharie faunas are present in strata succeeding the Cobourg Limestone, which bears only a Normanskill fauna.

A comparison of the Lowlands-Anticosti faunal succession with that of the Maravillas Chert of the Marathon region of Texas shows that Canajoharie, lower Lorraine, and uppermost Ordovician graptolite assemblages are not represented in the Maravillas Chert. The indicated lacunae make it unlikely that the upper part of the Marathon succession can serve as the standard reference section for the Middle-Upper Ordovician of North America.

The "post-Normanskill" graptolite fauna of the Appalachian geosyncline is characterized by many endemic forms and the absence of graptolites typical of the Pacific Faunal Province. The Appalachian fauna reached maximum development during Utica deposition, but did not survive through the great influx of Lorraine clastic material except on Anticosti Island, which was not affected by late Ordovician orogenic movements.