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 existences of the vegetable kingdom, is in many instances a deadly poison to those of the animal. The grasses and water-lilies 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 favorable 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