1. Following karyogamy and the two meiotic divisions, the probasidium of Tulasnella produces from its summit commonly four inflated epibasidia; into these migrate the nuclei and protoplasm of the basal cell; when the latter has been exhausted the epibasidia are separated from it by septa across their bases. In T. violea, T. fuscoviolacea, T. eichleriana, and T. lactea a third mitosis occurs in the epibasidia; following this each epibasidium elongates and upon a filament produced from its apex bears a binucleate basidiospore. In T. tulasnei there is no mitosis in the epibasidia. 2. Similarities existing between the Tulasnella basidium and that of the Tremellaceae argue the close relation of the two types; the tremellaceous basidium may be regarded as having evolved from the tulasnellaceous by the formation of basidial septa at an earlier stage in basidial ontogeny. Similarly the existence of transitional forms (among them the fungus described as T. anceps) argues the close relation of the Tulasnella basidi...