IV. Spores naked, on conspicuous threads, rarely compacted, small HYPHOMYCETES. Fertile threads compacted, sometimes cellular-- Stem or stroma compound-- Spores dry, volatile _Isariacei._ Mass of spores moist, diffluent _Stilbacei._ Fertile threads, free or anastomosing-- Fertile threads dark, carbonized-- Spores mostly compound _Dematiei._ Fertile threads not carbonized-- Very distinct-- Spores mostly simple _Mucedines._ Scarcely distinct from mycelium-- Spores profuse _Sepedoniei._ DIVISION II. SPORIDIIFERA. _Sporidia in Asci._ V. Fertile cells seated on threads, not compacted into a hymenium PHYSOMYCETES. Threads felted, moniliform-- Sporangia irregular _Antennariei._ Threads free-- Sporangia terminal or lateral _Mucorini._ Aquatic _Saprolegniei._ VI. Asci formed from the fertile cells of a hymenium ASCOMYCETES. Asci often evanescent-- Receptacle clavæform-- Asci springing from threads _Onygenei._ Perithecia free-- Asci springing from the base _Perisporiacei._ Asci persistent-- Perithecia opening by a distinct ostiolum _Sphæriacei._ Hard or coriaceous, hymenium at length exposed _Phacidiacei._ Hypogæous; hymenium complicated _Tuberacei._ Fleshy, waxy, or tremelloid; hymenium mostly exposed _Elvellacei._ IV. USES.