In this paper the author reviewed the arguments by which the geologists of Switzerland endeavour to prove that the so-called, “orographic” lakes are essential parts of the architecture of the Alps. He showed from detailed sections of one or two lakes, particularly of the Lake of the Four Cantons, that the amount of denudation, which the surrounding rocks had suffered, demonstrated that the lakes must be greatly younger than the plication of the strata of the Alpine chain; that from the known effects of subaerial denudatoni, the lakes must be, in a geological sense, quite modern; and that the Alpine lakes possessed no distinctive features which entitled them to be considered apart from the numerous lakes which are scattered over northern Europe and America. He regarded the enormous development of lakes at the present period in northern latitudes as a fact which could not be explained by reference to subterranean movements.