There are few groups, even among the notorious pyrenomycetes, that have been the source of new species to such an extent as the one covered by this monograph. Its author recognizes a big central and rather heterogeneous genus Pleospora (with 100 species) and some affiliated smaller genera, Platyspora, a new genus (3 species), Clathrospora (8 species), and Pyrenophora (7 species). 71 species are excluded from these genera. Dr. Wehmeyer had very profitable hunting, judging from the vast number of synonyms he admits and discusses under the accepted species. One would conclude that quite a number of the species as he defines them are broadly conceived or very variable. In the Chapter “Nomina dubia, confusa, nuda, etc.” 62 specific names are treated; and in the Chapter “Species non vidi” no less than 223 specific names are listed or discussed. Thus, it would seem that there is still ample opportunity for further hunting and for redescription of as yet insufficiently known species. Dr. Wehmeyer has striven to arrange the species of Pleospora known to him into subgenera, sections, and series: the probable phylogenetic relationships are presented in a chart. The 25 plates depict spores.