Let us remark further, at this stage, that, judging from the generally received geological evidence in the case, very little time seems to be allowed by the author of the “Vestiges” for that miraculous process of transmutation through which the low algæ of our sea-shores are held to have passed into high orders of plants which constitute the prevailing British flora. The boulder clay, which rises so high along our hills, and which, as shown by its inferior position on the lower grounds, is decidedly the most ancient of the country’s superficial deposits, is yet so modern, geologically, that it contains only recent shells. It belongs to that cold, glacial, post-Tertiary period, in which what is now Britain existed as a few groupes of insulated hill-tops, bearing the semi-arctic vegetation of our fourth flora,—that true _Celtic_ flora of the country which we now find, like the country’s Celtic races of our own species, cooped up among the mountains. The fifth or Germanic flora must have been introduced, it is held, at a later period, when the climate had greatly meliorated. And if we are to hold that the plants of this last flora were _developed_ from sea-weed, not propagated across a continuity of land from the original centre in Germany, or borne by currents from the mouths of the Germanic rivers,—the theory of Mon. C. Martins,—then must we also hold that that development took place since the times of the boulder clay, and that fucoids and confervæ became dicotyledonous and monocotyledonous plants during a brief period, in which the _Purpura lapillus_ and _Turritella terebra_ did not alter a single whorl, and the _Cyprina islandica_ and _Astarte borealis_ retained unchanged each minute projection of their hinges, and each nicer peculiarity of their muscular impressions. _Creation_ would be greatly less wonderful than a sudden transmutative process such as this, restricted in its operation to groupes of English, Irish, and Manx plants, identical with groupes in Germany, when all the various organisms around them, such as our sea-shells, continued to be exactly what they had been for ages before. A process of development from the lowest to the highest forms, rigidly restricted to the flora of a country, would be simply the miracle of Jonah’s gourd several thousand times repeated.