Such are some of the forms and structures of fishes that swam in the seas from which were deposited the sediment that has hardened into the " old red sandstones" of Great Britain, Russia, and other parts of the world. And in this process of consolidation the carcases of the fishes entombed in the primaeval mud have had their share. For, just as a plaster cast boiled in oil derives greater density and durability from that addition, so the oily and other azotized and ammoniacal principles of the decomposing fish operated upon the imme diately surrounding sand so as to make it harder and more compact than the sediment not reached by the animal princi ples. Accordingly it has happened that in the course of the upheaval and disturbance of old red strata, parts of it, broken up and exposed to the action of torrents, have been reduced to detritus, and washed away, with the exception of certain nodules, generally of a flattened elliptic form, which are harder than the surrounding sandstone. Such nodules form the bed of many a mountain stream in " old red sandstone " districts of Scotland. If one of these nodules be cleft by a smart and well-applied stroke of the hammer, the cause of its superior density will be seen in a more or less perfect speci men of the fossilized remains of some animal, most commonly a fish.
But the placoganoid and lepidoganoid, heterocercal and notochordal, fishes of the Devonian epoch existed in such vast shoals in certain favourable inlets, that the whole mass of the sedimentary deposits has been affected by the decomposing remains of successive generations of those fishes. The De vonian flagstones of Caithness are an instance. They owe
their peculiar and valuable qualities of density, tenacity, and durability wholly to the dead fishes that rotted in their primitive constituent mud. From no other part of the world, perhaps, can a large flagstone be got, which a builder could set on its edge with assurance of its holding long together in that position. A great proportion of the county of Caithness formed, before its upheaval, the bottom of what may truly be termed a " piscina mirabilis." Yet there are minds, who, cognizant of the won derful structures of the extinct Devonian fishes—of the evi dence of design and adaptation in their structures—of the altered nature of the sediment surrounding them, and its dependence on the admixture of the decomposing and dissolved soft parts of the old fish—would deliberately reject the conclu sions which healthy human reason must, as its Creator has constituted it, draw from such proofs of His operations. There are now individuals, one at least,* who prefer to try to make it be believed that God had recently, and at once, called into being all these phenomena ; that the fossil bones, scales, and teeth, had never served their purpose—had never been recent—were never truly developed, but were created fossil ; that the creatures they simulate never actually existed ; that the superior hardness of the inclosing matrix was equally due to primary creation, not to any secondary cause ; that the geological evidences of superposition, successive stratification, and upheaval were, equally with the palaeontological evidences, an elaborate design to deceive and not instruct !