Our science has been characterized as one whose goal today is its starting-point tomorrow. Nothing, therefore, can be more suitable to an occasion of this kind than a glance at some of those questions at present most actively discussed, and on which we have within the last few months been reading the arguments and conclusions of some of our ablest workers. We may even venture to make some modest suggestions as to the manner of possible settlement of these questions, and thus aid in clearing the way for those advances which in the near future must leave our present standpoint far in the rear. Such a review must necessarily be discursive and fragmentary—a sort of conglomerate in its material, but some consistency may be given to it by regarding its several topics in their relation to the foundation and building up of our continents, one of the great . . .