the Jurassic deposits are concealed by those of the Cretaceous epoch above them, these being also partially hidden under the later Tertiary beds. Let us see, then, what this inland sea has to tell us of the organic world in the Jurassic epoch. At that time the region where Lyme-Regis is now situated in modern England was an estuary on the shore of that ancient sea. About forty years ago a discovery of large and curious bones, belonging to some animal unknown to the scientific world, turned the attention of naturalists to this locality, and since then such a quantity and variety of such remains have been found in the neighborhood as to show that the Sharks, Whales, Porpoises, etc., of the present ocean are not more numerous and diversified than were the inhabitants of this old bay or inlet. Among these animals, the Ichthyosauri (Fish-Lizards) form one of the best-known and most prominent groups. They are chiefly found in the Lias, the lowest set of beds of the Jurassic deposits, and seem to have come in with the close of the Triassic epoch. It is greatly to be regretted that all that is known of the Triassic Reptiles antecedent to the Ichthyosauri still remains in the form of original papers, and is not yet embodied in text-books. They are quite as interesting, as curious, and as diversified as those of the Jurassic epoch, which are, however, much more extensively known, on account of the large collections of these animals belonging to the British Museum. It will be more easy to understand the structural relations of the latter, and their true position in the Animal Kingdom, when those which preceded them are better understood. One of the most remarkable and numerous of these Triassic Reptiles seems to have been an animal resembling, in the form of the head, and in the two articulating surfaces at the juncture of the head with the backbone, the Frogs and Salamanders, though its teeth are like those of a Crocodile. As yet nothing has been found of these animals except the head,--neither the backbone nor the limbs; so that little is known of their general structure. [Illustration: Fig. 1. An Ichthyosaurus.]