The subject will be arranged under the following headings. Nomenclature and Classification: Bringing out the attitude of the taxonomist and the bearing it has on the selection of an appropriate name for these intertriginous (primarily and essentially) ringworms. Etiology: The flora of normal skins. The rôle of bacteria, blastomycetes and hyphomycetes—are the last mentioned solely responsible for everything charged against them in epidermophytosis? A catalog and distribution (anatomic and geographic) of the various species reported. The status of the dermatophytids. Laboratory Diagnosis. Hygiene: The viability of ringworm material "extra corpore." Histopathology. Rational Therapeutics: What can the laboratory offer in this direction? Before proceeding to the body of this paper, I wish to say that I have attempted to present the case in such a way that the reader will maintain a point of view in which he can judge the situation for himself; I