The Early Eocene (Ypresian) dinoflagellate cyst assemblage described by PASTIELS (1948) is reassessed, on the basis of an examination of surviving type material. At least twenty-eight different taxa are recognized. The new species Cannosphaeropsis williamsii and the new combinations Nematosphaeropsis reticulensis (PASTIELS, 1948) and Tityrosphaeridium exilimurum (DAVEY and WILLIAMS, 1966a) are proposed. Emended diagnoses are formulated for the families Deflandreaceae EISENACK, 1954 and Wetzeliellaceae VOZZHENNIKOVA, 1961 and for the species N. reticulensis, Glaphyrocysta exuberans (DEFLANDRE and COOKSON, 1955) and G. pastielsii (DEFLANDRE and COOKSON, 1955). A neotype is selected for G. exuberans and a lectotype for N. reticulensis . The morphology of Polysphaeridium belgicum SARJEANT in DAVEY et al , 1969, and the problems presented by the generic separation of Polysphaeridium and Dapsilidinium , as comprehended by BUJAK et al. , 1980b, are discussed. It is shown that, whereas there is great uniformity in Early Eocene assemblages between northeast Europe and the Grand Banks, offshore eastern Canada, the assemblages of the latter region differ in detailed composition from those of the Labrador and Scotian Continental Shelves (herein termed the "Bujak" and "Brideaux" Associations) and vary markedly from those recorded in other parts of the world.