SummaryMaterial from the H. A. Nicholson collection, University of Aberdeen, provides information on three of Nicholson's species. Syntypes of Favistina calicina are described and the lectotype designated. Topotypes of Nyctopora billingsii are compared with an earlier description of the type thin sections. Columnopora cribriformis is considered synonymous with Calapoecia huronensis Billings, itself a poorly understood species; redescription of the type of the latter species shows it to be separate from C. canadensis Billings. Calapoecia ungava Cox is reinterpreted with a lectotype designated, and Nicholson material is placed with this species. All specimens are from eastern North America and of Upper Ordovician age excluding the Middle Ordovician N. billingsii and C. canadensis.