CHAPTER XIII.

Successors of the exterminated Tribes.—The Gap slowly filled. — Proof that the Vegetation of a Formation may long survive its Animal Tribes. Probable Cause. -Immensely extended Period during which Fishes were the Master-existences of our Planet. Extreme Folly of an Infidel Objection illustrated by the Fact. Singular Analogy between the History of Fishes as Individuals and as a Class. - Chemistry of the Lower Formation. - Principles on which the Fish-enclosing Nodules were probably formed. Chemical Effect of Animal Matter in discharging the Color from Red Sandstone. — Origin of the prevailing tint to which the System owes its Name. Successive Modes in which a Metal may exist. The Restorations of the Geologist void of Color. — Very different Appearance of the Ichthyolites of Cromarty and Moray.

THE period of death passed, and over the innumerable dead there settled a soft, muddy sediment, that hid them from the light, bestowing upon them such burial as a November snow-storm bestows on the sere and blighted vegetation of the previous summer and autumn. For an unknown space of time, represented in the formation by a deposit about fifty feet in thickness, the waters of the depopulated area seem to have remained devoid of animal life. A few scales and plates then begin to appear. The fish that had existed outside the chasm seem to have gradually gained upon it, as their numbers increased, just as the European settlers of America have been gaining on the backwoods, and making themselves homes amid the burial-mounds of a race extinct for centuries. For a lengthened period, however, these finny settlers must have been comparatively few mere squatters

in the waste. In the beds of stratified clay in which their

remains first occur, over what we may term the densely crowded platform of violent death, the explorer may labor for hours together without finding a single scale.

It is worthy of remark, however, that this upper bed abounds quite as much in the peculiar vegetable impressions of the formation as the lower platform itself. An abundance equally great occurs in some localities only a few inches over the line of the exterminating catastrophe. Thickets of exactly the same algæ, amid which the fish of the formation had sheltered when living, grew luxuriantly over their graves when dead. The agencies of destruction which annihilated the animal life of so extended an area, spared its vegetation; just as the identical forests that had waved over the semicivilized aborigines of North America continued to wave over the more savage red men, their successors, long after the original race had been exterminated. The inference deducible from the fact, though sufficiently simple, seems in a geological point of view a not unimportant one. The flora of a system may long survive its fauna; so that that may be but one formation, regarded with reference to plants, which may be two or more formations, regarded with reference to animals. No instance of any such phenomenon occurs in the later geological periods. The changes in animal and vegetable life appear to have run parallel to each other from the times of the tertiary formations down to those of the coal; but in the earlier deposits the case must have been different. The animal organisms of the newer Silurian strata form essentially different groups from those of the Lower Old Red Sandstone, and both differ from those of the Cornstone divisions; and yet the greater portion of their vegetable remains seem the same. The stem-like impressions of the fucoid bed of the Upper Ludlow Rocks cannot be distinguished from

those of the ichthyolite beds of Cromarty and Ross, nor these again from the impressions of the Arbroath pavement, or the Den of Balruddery. Nor is there much difficulty in conceiving how the vegetation of a formation should come to survive its animals. What is fraught with health to the exist ences of the vegetable kingdom, is in many instances a deadly poison to those of the animal. The grasses and waterlilies of the neighborhood of Naples flourish luxuriantly amid the carbonic acid gas which rests so densely over the pools and runnels out of which they spring, that the bird stoops to drink, and falls dead into the water. The lime that destroys the reptiles, fish, and insects of a thickly inhabited lake or stream, injures not a single flag or bulrush among the millions that line its edges. The two kingdoms exist under laws of life and death so essentially dissimilar, that it has become one of the common-places of poetry to indicate the blight and decline of the tribes of the one by the unwonted luxuriancy of the productions of the other. Otway tells us, in describing the horrors of the plague which almost depopulated London, that the "destroying angel stretched his arm" over the city,

"Till in th' untrodden streets unwholesome grass

Grew of great stalk, and color gross,

A melancholic poisonous green."

The work of deposition went on; a bed of pale yellow saliferous sandstone settled, tier over tier, on a bed of stratified clay, and was itself overlaid by another bed of stratified clay in turn. And this upper bed had also its organisms. The remains of its sea-weed still spread out thick and dark amid the foldings of the strata, and occasionally its clusters of detached scales. But the circumstances were less favora

ble to the preservation of entire ichthyolites than those under which the organisms of the lower platform were wrapped up in their stony coverings. The matrix, which is more micaceous than the other, seems to have been less conservative, and the waters were probably less still. The process went on. Age succeeded age, and one stratum covered up another. Generations lived, died, and were entombed in the ever-growing depositions. Succeeding generations pursued their instincts by myriads, happy in existence, over the surface which covered. the broken and perishing remains of their predecessors, and then died and were entombed in turn, leaving a higher platform, and a similar destiny to the generations that succeeded. Whole races became extinct, through what process of destruction who can tell? Other races sprang into existence through that adorable power which One only can conceive, and One only can exert. An inexhaustible variety of design expatiated freely within the limits of the ancient type. The main conditions remained the same - the minor details were dissimilar. Vast periods passed; a class low in the scale still continued to furnish the master existences of creation; and so immensely extended was the term of its sovereignty, that a being of limited faculties, if such could have existed uncreated, and witnessed the whole, would have inferred that the power of the Creator had reached its extreme boundary, when fishes had been called into existence, and that our planet was destined to be the dwelling-place of no nobler inhabitants. If there be men dignified by the name of philosophers, who can hold that the present state of being, with all its moral evil, and all its physical suffering, is to be succeeded by no better and happier state, just because "all things have continued as they were for some five or six thousand years, how much sounder and more conclusive would the inference have been which

could have been based, as in the supposed case, on a period perhaps a hundred times more extended?

There exist wonderful analogies in nature between the geological history of the vertebrated animals as an order, and the individual history of every mammifer - between the history, too, of fish as a class, and that of every single fish. "It has been found by Tiedemann," says Mr. Lyell, “that the brain of the fœtus in the higher class of vertebrated animals assumes in succession the various forms which belong to fishes, reptiles, and birds, before it acquires those additions and modifications which are peculiar to the mammiferous tribes." "In examining the brain of the mammalia," says M. Serres," at an early stage of life, you perceive the cerebral hemispheres consolidated, as in fish, in two vesicles isolated one from the other; at a later period you see them affect the configuration of the cerebral hemispheres of reptiles; still later, again, they present you with the forms of those of birds; and finally, at the era of birth, the permanent forms which the adult mammalia present." And such seems to have been the history of the vertebrata as an order, as certainly as that of the individual mammifer. The fish preceded the reptile in the order of creation, just as the crustacean had preceded the fish, and the annelid the crustacean. Again, though the fact be somewhat more obscure, the reptile seems to have preceded the bird. We find, however, unequivocal traces of the feathered tribes in well-marked foot-prints impressed on a sandstone in North America, at most not more modern than the Lias, but which is generally supposed to be of the same age with the New Red Sandstone of Germany and our own country. In the Oolite at least one, perhaps two formations later the bones of the two species of mammiferous quadrupeds have been found, apparently of the marsu