The study of the interesting agaric family, Gomphidiaceae, was undertaken in 1958. Since that time collections have been made and examined from Idaho, Washington, Oregon, Montana, and the Upper and Lower Peninsulas of Michigan. Collections from New Hampshire failed to yield any specimens in this genus. All but three of the North American species have been studied from fresh material. In addition, the help of Dave Largent in sending fresh material via air mail from California is acknowledged. A large number of collections of dried material were examined at the University of Michigan Herbarium. Notes and photographs at the University of Michigan Herbarium by C. H. Kauffman and A. H. Smith were made available and invaluable assistance was given by Dr. Smith during the course of this study. I am also indebted to the curators of the following herbaria for the loan of or permission to study material which greatly aided in this study: Naturhistoriska Riksmuseet, Stockholm, Sweden; New York State Museum, Albany; New York Botanical Garden; Royal Botanic Gardens, Kew; and the Farlow Herbarium, Harvard University.