Before leaving the Eocene, or rather the London clay of the Eocene, we will give a drawing of a fossil in our possession. The drawing opposite represents a piece of fossil wood, pierced through and through by Teredinæ, a boring mollusk allied to the Teredo, which still proves so destructive to our vessels. Although the wood is converted into a stony mass, and in some parts covered by calcareous matter, the same as is found in the septaria, so common in these beds, to which we shall presently direct attention, still the grain and woody texture are most distinct. This wood was once probably floating down what we now call the Thames, when these piercing, boring mollusks seized hold upon it, penetrated its soft texture, and lived, moved, and had their being down at the bottom of the river in their self-constructed chambers. Time rolled on, and the log of wood is floated upon the shore, and there it lies to harden and to dry; again the log is drifted away, and, buried in some soft bed of clay, is preserved from rotting. In process of time it again sees the light; but now saturated by argillaceous material, and when hardened by the sun, becomes the petrifaction such as we see it. [Illustration: WOOD PERFORATED RY TEREDINA PERSONATA, LONDON CLAY. ] Here let us refer to the septaria, of which we have just spoken; two specimens lie before us, which we will briefly describe. In one (1) the clay is in distinct lozenge-shaped masses of a blue colour, while veins of calcareous spar or crystallized carbonate of lime surround these, which are capable of a beautiful marble-like polish; in the other (2) the clay is of the same colour, only in larger proportions, and the spar is of a deep brown colour, while here and there portions of iron pyrites may be seen; they become beautiful ornaments in a room when cut and polished. It should be added, that the septaria are not without their economic uses, being extensively used as cement after being stamped and burnt. [Illustration: SEPTARIA ] Here we may leave this brief sketch of the Eocene, or lowest beds of the Tertiary. A new creation has been introduced to our view; and although we still wait for the coming of man—the lord and interpreter of all—the contemplation of these successive acts and centres of creation fills our minds with renewed admiration and reverence of Him for whom, and by whom, and to whom are all things. Thus “even Geology, while it has exhumed and revivified long buried worlds, peopled with strange forms in which we can feel little more than a speculative interest, and compared with which the most savage dweller in the wilderness of the modern period—jackal, hyæna, or obscene vulture—is as a cherished pet and bosom friend, has made for us new bonds of connexion between remote regions of the earth as it is, on account of which we owe it a proportionate share of gratitude.”[117] No. II.—_The Miocene._