In these strata the remains of organised beings are first found, consisting of zoophytes, crustacea (chiefly Trilobites, fig. 11), nautili, crinoidii (stone lilies), and a few ganoid (plate-covered) fishes; these lower forms of animal life in some parts abound in the most prodigious numbers. There must, of course, have been vegetables of some kind previously formed to constitute nourishment for these animals, but scarcely any remains of such exist, except in a few localities. The Trilobites were amongst the first creatures inhabiting our globe, and it is a curious fact to contemplate, that their eyes (fig. 12) should have been preserved perfect; they present one of those wonderful objects which carry one's thoughts backwards to the early ages of the world, probably many millions of years, and yet it is found by the peculiar structure of the eyes of these Trilobites that they were placed at the bottom of the sea with perfect power to look upwards at the light of the sun through the transparent waters. The same hand and the same power had then Divine care and solicitude for the well-being of His creatures, as great as He has for those of later ages, and these first-formed beings exactly correspond with the account of the creation of animals given in the book of Genesis, "And God said, let the waters bring forth abundantly the moving creature that hath life." [Illustration: FIG. 12.--EYE OF TRILOBITE.] At the end of the "transition period"--after ages of long-continued disintegration of the rough surface of the earth, and its deposition in strata--after thousands of generations of crustaceans, molluscs, and zoophytes had lived and died, depositing their shells at the bottom of the seas, so as to form strata of the carbonate of lime--a great and terrific convulsion of nature put a stop to all this quiet and systematic order of things; for through these long reaches of time, the physical laws of nature had continued to exert their influence, the bulk of the world had gone on radiating its heat into space, and, as a necessary result, had gradually contracted in size. Now, this radiation had doubtless been much retarded by the badly-conducting surface of solid matter which had everywhere covered it, but, although retarded, it could not be prevented, and although the crust of solid matter may already have been several miles in thickness, yet this in relation to the bulk of the earth would hold but the proportion of the paper on the surface of a twelve-inch globe. As the fluid mass of the earth continued to contract, there would of course be a great stress or crushing-power exerted on the crust, both by its own gravity and that of the air which surrounded it, and about this period it appears to have given way over the greatest portion of the globe, producing enormous rents and fractures, seen in every country in the faults and dislocations of these primitive and transition strata, some of