Most authorities think that the fungus first described by Castellani, in 1910,1 as Epidermophyton rubrum is identical with Trichophyton purpureum (Bang, 19102) and Trichophyton rubidum (Priestley, 19173) which were subsequently described. Castellani4 still considers the fungus that he reported to be an epidermophyton and classifies it as such in his recent articles in the Archives of Dermatology and Syphilology. All observers agree that this fungus is a superficial invader, occasionally being found in a wide variety of mycologic conditions, including the macerative and vesicular types of dermatophytosis, tinea cruris, tinea circinata and onychomycosis. We were unable to find any reference in the literature to cases in which this fungus was found to play a part in the production of deep infection or in which the hair follicle was invaded. However, inoculation of guinea-pigs with cultural material was successful in some instances. Bang reported one positive result