The genus Erythroneura was divided by W. L.. McAtee and later confirmed by Wm. Robinson, into several groups by the venation of the front wing. The maculata group was characterized particularly by the absence of the M-Cu cross-vein and by the base of cell M4 being angulate. In dissecting and studying the male genitalia of several hundred specimens of this group a good many undescribed forms have been found. It is the purpose of the present paper to begin a study of the entire group, redescribing named species wliere necessary and adding the new forms. Drawings and photographs have been made but will be published later.