Forty collections, comprising all known European species of the ‘stercorarius group’ of the genus Coprinus except C. radicans Romagn., were examined, including the type specimens of C. cinereofloccosus P. D. Orton, C. saccharomyces P. D. Orton, and C. martinii P. D. Orton. A new species, C. laanii Kits van Wav. is described. A regrouping of and key to the ‘stercorarius group’ is given and mainly based on spore characters. It is argued that C. cineratus Quél, and C. tuberosus Quél, are conspecific with C. stercorarius as originally described by Fries and that C. velox Godey (= C. stercorarius Fr. sensu Kühn. & Romagn.) belongs to this group. Coprinus saccharomyces P. D. Orton was found to be identical with the 2-spored form of C. stercorarius (Scop.)ex Fr., which — as such — was hitherto unknown. The ultrasonic desintegrator helped to explain the nature of the black dots on the spores of C. narcoticus and C. laanii, which are believed to be caused by the wrinkling of the perisporial sac. The terms sporogram, cystidiogram, and basidiogram are introduced.