There can be no doubt, too, that geology would profit, if we could push our researches nearer to the Pole, and force our way through the great barrier of the Polar ice. It is highly desirable, too, that we should know more of that interesting class of animals, the Mollusca, both terrestrial and aquatic, fresh-water and salt-water. Again: what a wide field of inquiry is opened up by the Polar glaciers; their extent, their elevation, their range, and the effects produced by the slow but continuous motion of those huge ice-rivers over the surface of the country. And the botanist has a right to calculate upon the discovery of many precious forms of vegetable life in the Unknown Region. The Arctic flora is by no means abundant, but it is peculiarly interesting. In Greenland, besides numerous mosses, lichens, algæ, and the like, flourish three hundred kinds of flowering plants, all of which are natives of the Scandinavian peninsula; and Dr. Joseph Hooker remarks that they exhibit scarcely any admixture of American types, though these are found on the opposite coast of Labrador. It would seem probable that in the warm period which preceded the Glacial Age, the Scandinavian flora spread over the entire area of the Polar Regions; but that during the Age of Ice it was gradually driven within its present limits, only the hardier types surviving the blight of the long lingering winter. And what would be the gain to the zoologist? Why, it is a well-known fact that life abounds in the Arctic waters, and especially those minute organisms which play so important a part in the formation of sedimentary deposits, and help to build up the terrestrial crust. We have much to learn, moreover, of the habits and habitats of the fish, the echinoderms, the molluscs, the corals, the sponges of the extreme Northern Seas. There are questions connected with the migrations of birds which can be elucidated only by an exploration of the Unknown Region. Multitudes which annually visit our shores in the winter and spring, return in summer to the far North. This is their regular custom, and obviously would not have become a custom unless it had been found beneficial. Therefore we may assume that in the zone they frequent they find some water which is not always frozen; some land on which they can rest their weary feet; and an adequate supply of nourishing food. From Professor Newton we adopt, in connection with this consideration, a brief account of the movements of one class of migratory birds,--the Knots.[1]