[103] _Castor fiber._—Some of the European naturalists appear to be in doubt, whether or not the beavers of Europe are of the same species with ours, from the circumstance of the former not erecting habitations for themselves, thus appearing to differ at least in habit, from the North American, (which are usually but improperly called, Canada beaver, as they are not confined to Canada, but are found far south in the United States, and east to the confluence of the Ohio and Mississippi,) but it is possible, that the aboriginal manners of the European beavers, corresponded with those of ours, and that necessity, resulting from the population of the country by civilized man, compelled them to resort to a different mode of life, to escape the certain destruction, with which the great demand for their fur threatened them. But as the European beaver is smaller than ours, other naturalists have regarded it as a distinct species. In those districts of country of North America, from which they have not yet been exterminated, and which are populated by the whites, as particularly on the Mississippi, above the Ohio, and below St. Louis, we have not heard that they build, but it is more than probable, that, as in Europe, they change their mode of life, in order to be the more effectually concealed from view. From subsequent observation, we have learned, that the beaver does not attempt to dam large streams, perceiving at once the impracticability of the undertaking: his object in damming a stream appears to be, to preserve a constancy in the height of the water, in order that the entrance to his habitation in the bank may be concealed, and that the curious conical edifice may not be destroyed by a sudden flood, or too much exposed by a deficiency of water. An Indian informed us, that in his time, he has caught three specimens of this animal, that had each a large white spot on the breast. Singular accounts of this animal are given us by the hunters, but which we had no opportunity of verifying. Three beavers were seen cutting down a large cotton-wood tree; when they had made considerable progress, one of them retired to a short distance, and took his station in the water, looking steadfastly at the top of the tree. As soon as he perceived the top begin to move towards its fall, he gave notice of the danger to his companions, who were still at work, gnawing at its base, by slapping his tail upon the surface of the water, and they immediately ran from the tree out of harm's way. The spring beaver are much better for commerce than those of the autumn and early winter, as the fur is longer and more dense. But the beaver taken in the vicinity of the Rocky Mountains is almost equally good during the year.