The sequence of Devonian ammonoid faunas in North America is reviewed,and comparisons are made with the known European and North African successions. All the Middle and Upper Devonian major zones of Europe are recognized apart from those of the uppermost Famennian, but some evidence for those is recorded. As a whole the American faunas, despite their relative rarity, show remarkable affinity, in order and nature, with their European equivalents. Several European genera are recorded for the first time from the American Devonian,and these include: Anetoceras, Subanarcestes, Cabrieroceras, Wedekindella, Sobolewia, Maenioceras, Pharciceras, Archoceras, Chelioceras, Rectoclymenia, Cyrtoclymenia, and Cymacclymenia. New species of Sobolewia, Cyrtoclymenia and Rectoclymenia are proposed. A tentative series of zonal indices is selected for the American Devonian. Attention is drawn to the Eifelian affinity of the few known Onondaga (Nedrow) goniatites from New York State. Upper Givetian goniatites are noted in the lower Fort Creek Shale of the Northwest Territories, Canada. Goniatites amplexus, of the Tully Limestone in New York State, is shown to be a Pharciceras. The Gowanda Shale on Lake Erie shore contains a fauna including Cheiloceras. A Sporadoceras is described from the Ellicott Shale of New York. Devonian clymenids are noted from the Chonopectus Sandstone of Iowa, and it is Cyrtoclymenia from this fauna which has been responsible for the erroneous records of Agoniatites in the American Kinderhookian Series. It is suggested that the Devonian-Carboniferous boundary at Burlington should be drawn between the Chonopectus Sandstone and the overlying Hampton; that is, within beds commonly referred to the Lower Mississippian.