1. Hypomyces lactifluorum (Schw. ex Fr.) Tul. forms a true perithecium from spirally coiled ascogonia. A prosenchymatous wall surrounds the centrum. 2. Centrum development is characterized by downward growing pseudoparaphyses, typical of the Nectria Developmental Type. 3. Multinucleate ascogenous cells form croziers from which asci arise. Meiosis and mitosis form eight nuclei; a nucleolus is present.4. The chromosome number is n = 5. 5. A thickened apical cap with a pore, but no apical ring, is present on the ascus. 6. Two- and three-celled chlamydospores of the genus Blastotrichum were found.