The species, integrum Eaton, described from material collected in Washington and Oregon states, was designated by Eaton as the genotype of Cinygma. I have already (1926, Can. Ent. LVIII, 302) recorded the capture of adults of this species in the Coast range of British Columbia and at the time expressed some doubt as to whether all the species at present included in this genus were strictly congeneric. Since nymphal structures have been recognized by a number of recent workers as of great importance in furnishing distinguishing characters in the Heptagenine genera it was with considerable interest that I discovered among material collected in the Hope Mts., B. C. in 1932 by my assistant, Mr. A. N. Gartrell, a bred female adult of integrum, together with its nymphal exuvia, preserved in alcohol. A study of this exuvia soon convinced me that in the nymphal gills and mouth-parts there are excellent and in part unique structural details which should at once establish not only the validity of the genus but also its limitations and position in the group of allied genera.