The science which, from such _indicia_ as these, has succeeded in determining not only the class, but the very form and habits, of the animals which impressed them—no other traces remaining than those petrified footsteps, covered up and hidden for ages—presents subjects of study to the inquiring mind, which may well rank among the most valuable, as well as curious, of human research. Is it not wonderful enough, that organic impressions merely should have been transmitted so fresh and entire, as to admit of classification, equal in scientific precision to that of the families of living things? What matter of suggestive reflection, inscribed on every page of that history? The tribes which were created and flourished during the Permian-triassic age perished, their earthy parts in most cases were all again absorbed by the earth, dissipated or melted into the viewless air. Still there are memorials of their existence, enduring and indelible, not of bones and sinews, but of actions and habits, which the waters cannot obliterate, nor the floods wash away! Man, a being of a different mold,—and with him “Will all great Neptune’s ocean wash this blood Clean from my hand?” was the cry of instinctive dread—the foreboding of an assured conscience, that the foul and guilty deed could never be effaced from the memory, nor blotted from the records of creation. The foot-tread of the robber has tracked him to his den; the minutest stain of blood has established the crime of murder; a dream or vision of the night has pointed to the mangled corse; a word uttered years after all was forgotten, or a rude ditty chanted, have recalled the pictures of infancy, and the wanderer to his home. Here we behold, stamped upon the rock, legible as the law upon the tablets of the heart, intimations of the great universal law, that an act once committed cannot be canceled; that a cause will be followed by a sequence of effects; indefinite and ever-extending; and that the Divine Spirit, which drew illustrations from the fields and taught wisdom among the rocks of Horeb, still points the moral in these ineffaceable memorials—that the recording angel so traces in the book of life the story of every age, of every generation, of every individual, never to be lost nor forgotten in that eternity whither their works do all follow them.