dence for our study of these facts varies all the way from the vague conviction of the quarryman's judgment to the convictions that are founded on the closest scrutiny of the facts by men whose whole lives are devoted to the study of just such things with all skilled culture of the age to help them. In addition, then, to the quarryman's conviction, we have skilled students of science testifying that they find in these very stone quarries the materials for the exact study of plants and animal life. So complete are these materials that they satisfy all inquiry, and produce a conviction that in prying apart form the stone layers of the rocks the scientist is in reality opening the leaves of the past history of our world, and that in these buried leaves of sand stone and mud deposits of seas and lakes of former ages, he in uncovering not only the real shells and bones of the life of the period, but even the ripples marks of the waters that once covered them.
On Plate I we have a very good engraving from a photography of one of these rock frag-
