The more closely we study past creations, the more impressive and significant do the synthetic types, presenting features of the higher classes under the guise of the lower ones, become. They hold the promise of the future. As the opening overture of an opera contains all the musical elements to be therein developed, so this living prelude of the Creative work comprises all the organic elements to be successively developed in the course of time. When Cuvier first saw the teeth of a Wealden Reptile, he pronounced them to be those of a Rhinoceros, so mammalian were they in their character. So, when Sommering first saw the remains of a Jurassic Pterodactyl, he pronounced them to be those of a Bird. These mistakes were not due to a superficial judgment in men who knew Nature so well, but to this prophetic character in the early types themselves, in which features were united never known to exist together in our days. * * * * * The Jurassic epoch, next in succession, was a very important one in the history of Europe. It completed the junction of several of the larger islands, filling the channel between the central plateau of France and the Belgian island, as well as that between the former and the island of Bretagne, so that France was now a sort of crescent of land holding a Jurassic sea in its centre, Bretagne and Belgium forming the two horns. This Jurassic basin or inland sea united England and France, and it may not be amiss to say a word here of its subsequent transformations. During the long succession of Jurassic periods, the deposits of that epoch, chiefly limestone and clays, with here and there a bed of sand, were accumulated at its bottom. Upon these followed the chalk deposits of the Cretaceous epoch, until the basin was gradually filled, and partially, at least, turned to dry land. But at the close of the Cretaceous epoch a fissure was formed, allowing the entrance of the sea at the western end, so that the constant washing of the tides and storms wore away the lower, softer deposits, leaving the overhanging chalk cliffs unsupported. These latter, as their support were undermined, crumbled down, thus widening the channel gradually. This process must, of course, have gone on more rapidly at the western end, where the sea rushed on with most force, till the channel was worn through to the German Ocean on the other side, and the sea then began to act with like power at both ends of the channel. This explains its form, wider at the western end, narrower between Dover and Calais, and widening again at the eastern extremity. This ancient basin, extending from the centre of France into England, is rich in the remains of a number of successive epochs. Around its margin we find the Jurassic deposits, showing that there must have been some changes of level which raised the shores and prevented later accumulations from covering them, while in the centre