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 that collected by the Harri- 

 man Expedition ; that obtained by the writer during explora- 

 tions 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 the 

 collection is not remarkably large, it is probably the largest and 

 most complete, for the region, ever brought together. 



The text figures have been generously lent by the Smith- 

 sonian Institution. 



I am indebted to Mr. Bryant Walker, Dr. J. F. Whiteaves of 

 the Dominion Geological Survey, Dr. H. A. Pilsbry, of the 

 Academy of Natural Sciences, Philadelphia, and numerous 

 other correspondents, for advice and assistance ; and to the au- 

 thorities of the U. S. Geological Survey, the Dominion Geolog- 

 ical Survey, the Smithsonian Institution, and the U. S. National 

 Museum, for facilities for study and access to collections, for 

 all of which I am deeply grateful. 



Wm. H. Dall. 



Smithsonian Institution, 



Washington, D. C, Sept. 17, 1904. 



