NOTE THE following memoir has been prepared to bring together - and modernize the data existing in the literature, and to combine it with the new material obtained by the Harriman Expedition and such as was accessible elsewhere from the same region. In order to accomplish this, and because of the uniformity of boreal faunas all round the northern hemisphere, it has been necessary to examine the entire boreal fauna of North America, Greenland, and the adjacent parts of eastern Siberia. The material examined has been thnt collected by the Harriman Expedition that obtained by the writer during explorations in Alaska from 1865 to 1885, and now in the National Museum collections from various collaborators of the Museum, members of the Navy, the Revenue Marine, and the Geological Survey of the United States and certain material borrowed for examination from various sources. On the whole, though thc collection is not remarkably large, it is probably the largest and most cotnplete, for the region, ever brought together. The test figures have been generously lent by the Smithsonian Institution. I am indebted to Mr. Bq-ant Walker, Dr. J. F. Whiteaves of the Dominion Geological Survey, Dr. H. A...