the Scottish and Welsh Highlands, and intimately related to that of the Norwegian Alps; fifth, a flora which prevails over a large part of England and Ireland, ‘mingled with other floras, and diminishing slightly as we proceed westward:’ this bears intimate relation with the flora of Germany. Facts so remarkable would force the meanest fact-collector or species-demonstrator into generalization. The really ingenious man who lately brought them under notice (Professor Edward Forbes) could only surmise, as their explanation, that the spaces now occupied by the intermediate seas must have been dry land at the time when these floras were created. In that case, either the original arrangement of the floras, or the selection of land for submergence, must have been apposite to the case in a degree far from usual. The necessity for a simpler cause is obvious, and it is found in the hypothesis of a _spread of terrestrial vegetation from the sea into the lands adjacent_. The community of forms in the various regions opposed to each other merely indicates a distinct marine creation in each of the oceanic areas respectively interposed, and which would naturally advance into the lands nearest to it, as far as circumstances of soil and climate were found agreeable.” Such, regarding the origin of terrestrial vegetation, are the views of Maillet, Oken, and the author of the “Vestiges.” They all agree in holding that the plants of the land existed in their first condition as weeds of the sea. Let me request the reader at this stage, ere we pass on to the consideration of the experience-argument, to remark a few incidental, but by no means unimportant, consequences of the belief. And, first, let him weigh for a moment the comparative demands on his credulity of the theory by which Professor Forbes accounts for the various floras of the British Islands, and that hypothesis of transmutation which the author of the “Vestiges” would so fain put in its place, as greatly more simple, and, of course, more in accordance with the principles of human belief. In order to the reception of the Professor’s theory, it is necessary to hold, in the first place, that the creation of each species of plant took place, not by repetition of production in various widely-separated centres, but in some single centre, from which the species propagated itself by seed, bud, or scion, across the special area which it is now found to occupy. And this, in the first instance, is of course as much an assumption as any of those assumed numbers or assumed lines with which, in algebra and the mathematics, it is necessary in so many calculations to set out, in quest of some required number or line, which, without the assistance of the assumed ones, we might despair of ever finding. But the assumption is in itself neither unnatural nor violent; there are various very remarkable analogies which lend it support; the facts which seem least to harmonize with it are not wholly irreconcilable, and are,