While stationed at the Dominion Biological Laboratory at Cultus Lake, B. C., and conducting investigations on the sockeye salmon, Dr. W. E. Ricker spent some of his leisure time in collecting certain groups of aquatic insects and has generously presented the bulk of the material to the Royal Ontario Museum of Zoology. The Odonata, which were kindly sent to the writer, were collected in a most discriminating manner and include some interesting species hitherto unknown to the region. One new species, a Macromia, is described herewith, while the collection as a whole will be reported upon in a future paper.