SUMMARYA unique fungus characterized by the production of large, dark, multiseptate, fusiform chlamydospores is described and illustrated, and assigned to the new genusXylomyces, asX. chlamydosporis.The fungus has been found on several occasions on immersed dead, decaying wood, collected in a tide-water stream in southern Rhode Island, and is also known from a single collection made in Alabama. The new genus, placed in the Mycelia Sterilia of the Hyphomycetes, is suggestive of the fossil genusPluricellaesporites.