The aim of this study has been to compare the ontogenetic structures of as many species of Coprinus as possible in order to obtain a better insight into their mutual relationships. The sequence of development of the parts in the first phases of primordium development has been traced with greater precision here; several degrees of rupthymenial hymenophore development have been distinguished; the veil and pileipellis structures and the corresponding terminology have been critically discussed. Finally, an attempt has been made to establish phylogenetic relationships between about 27 species, but to acheive a higher degree of accuracy in this field, ontogenetic information concerning still more species is required.