The dermatophytes, fungi of various types causing diseases of the skin and hair, are at the present time in a state of confusion from the point of view of identification and classification. This confusion is the result of two factors: First, the generic classifications used have been based chiefly on the parasitic aspect of these fungi in the hair, while the specific determinations have been based on the gross appearance of the fungi in culture. Second, the morphologic characters of the fungi are limited, and their growth and sporulation in culture, as has been found to be true of all fungi imperfecti, are extremely variable. The need for a simplified system of classification that would eliminate the creation of genera on the basis of a clinical diagnosis has been recognized for many years. Several attempts have been made to establish a classification based on the morphology of the fungi,