From the many misidentifications in herbaria and the contradictions between the descriptions of many authors it became evident that the species of Trichomanes included by Desvaux, Presl, van den Bosch and Copeland under the generic name Didymoglossum and those included by Presl, van den Bosch and Copeland under the name Microgonium were particularly poorly understood. A complete revision of this group has never been undertaken. LINDMAN’s paper (1903) is incomplete, being based only on the study of about 30 herbarium sheets; moreover, his conclusions are based on misinterpretation of several species. The treatments in local floras, as, e.g. STURM’s (1859) and MAXON’s (1926) are very good, but only a small number of species are involved. The name Didymoglossum was used for the first time by DESVAUX (1827); it was taken up by PRESL (1843), and COPELAND (1938), all on the generic level. Microgonium was established as a genus by PRESL (1843). Van den BOSCH (1861) and COPELAND (1938) maintened it as a separate genus.