The Bear, Badger, and Wolverine go along with little variation. Probably the Coon does the same; the enormous rise in 1867 from an average of 3,500 per annum. to 24,000 was most likely a result of accidental accumulation and not representative of any special abundance. Finally, each and every line manifests extraordinary variability in the '30's. It is not to be supposed that the population fluctuated so enormously from one year to another, but rather that the facilities for export were irregular. The case is further complicated by the fact that some of the totals represent part of this year and part of last; nevertheless, upon the whole, the following general principles are deducible: (a) The high points for each species are with fair regularity 10 years apart. (b) In the different species these are not exactly coincident. (c) To explain the variations we must seek not the reason for the increase--that is normal--but for the destructive agency that ended the increase. This is different in three different groups. First. The group whose food and enemies fluctuate but little. The only examples of this on our list are the Muskrat and Beaver, more especially the Muskrat. Its destruction seems to be due to a sudden great rise of the water after the ice has formed, so that the Rats are drowned; or to a dry season followed by severe frost, freezing most ponds to the bottom, so that the Rats are imprisoned and starve to death, or are forced out to cross the country in winter, and so are brought within the power of innumerable enemies. How tremendously this operates may be judged by these facts. In 1900 along the Mackenzie I was assured one could shoot 20 Muskrats in an hour after sundown. Next winter the flood followed the frost and the Rats seemed to have been wiped out. In 1907 1 spent 6 months outdoors in the region and saw only 17 Muskrats the whole time; in 1901 the H. B. Co. exported over 11 millions; in 1907, 407,472. The fact that they totalled as high was due, no doubt, to their abundance in eastern regions not affected by the disaster. Second. The group that increases till epidemic disease attacks their excessively multiplied hordes. The Snowshoe-Rabbit is the only well-known case today, but there is reason for the belief that once the Beaver were subjected to a similar process. Concerning the Mice and Lemmings, I have not complete data, but they are believed to multiply and suffer in the same, way. Third. The purely carnivorous, whose existence is dependent on the Rabbits. This includes chiefly the Lynx and Fox, but in less degree all the small carnivores. In some cases such as the Marten, over-feeding seems as inimical to multiplication as under-feeding, and it will be seen that each year of great increase for this species coincided with a medium year for Rabbits.