Through the courtesy of Dr. McDunnough, I have recently been permitted to study many specimens of mayflies allied to the genus Iron, which were collected in Western Canada. Imagoes of both sexes and correctly associated nymphs of several species were included in the material, which was loaned to me from the Canadian National Collection. A study of these specimens, together with others in the Cornell University Collection, convinces me that two new genera are represented, which I designate respectively as Ironodes and Ironpsis.