Abstract: The classical differences between Otidea (Pers.) Bon. and Tarzetta (Cooke) Lamb. (Pustulana auct.) are evpluated and shown to be of slight taxonomic value. The structure of the excipulum is found to be identical in the two genera. On the other hand, they are clearly differentiated by certain sporal and cytological characters, an essential part of which are presented for the first time. The Otidea and Tarzetta spores belong to different types on the basis of the existence versus absence of a cyanophilic perispore-periplasm coating in mature spores. Staining with cotton blue proved to be very helpful in the study. It is concluded that the two genera should be kept separate, as has generally been done up till now, although on different and uncertain grounds.