Thus of eight genera of plants in the wealden, there are only four common to it and the oolites, but not a single species. Of the hundreds of zoophytes in the older formation, not one occurs in the newer. Twenty genera of insects existed in the period of the wealden, one only of which is prolonged from the antecedent period of oolitic life; one new genus of Crustacean (the Cypris), and five species; while the conchifera have little in common, save the mytilus and unio, and both of which, generically, have been transmitted from the carboniferous era. The fishes of the wealden consist of seven genera, of which only one is new, the Sphenonchus. The reptilians amount to eleven genera, three of which present remains in the oolitic group, Cetiosaurus, Chelonia, and Megalosaurus—same species in both. The Cetiosaurus belongs to the whale race of animals, and it is singular to find the tribe exhibiting the same stupidity, or hardihood it may be, in forsaking, then as now, their briny element, and seeking a grave in the clays and sands of fresh water shoals! The Hylæosaurus and Iguanodon were both found in the Tilgate Forest beds, but have been noticed under the fauna of the oolite series, as probably living in the age of, as they approach so closely in structure and size to, the reptilian types of the deposit; frequenting the woods and pastures, while their mighty cotemporaries were following their instincts in the seas and lakes of the district. It would thus appear that the close of the oolitic period of the earth’s history resembles the close of the carboniferous period, in the sudden transition from an exuberant to a remarkably barren display of vegetable fossils. In the comparative scantiness of the sauroid family of fishes, by which the outgoing of the coal era is likewise distinguished, we may fancy another point of analogy in the diminution of the monstrous reptilians that appears to have taken place after this series of deposits. May it be inferred that these two periods enjoyed a higher degree of temperature than has prevailed, either before or since, generally over the earth’s surface, and more certainly in these northern latitudes? Interred among the strata of both lie the remains of races, vegetable and animal, which have perished: and what we describe by kindred names are confined to climes and regions basking near the equator, and enlightened by other constellations. Then the alternating deposits of clay, lime, ironstone, coal, salt, gypsum, speak of lakes and estuaries, rolling rivers and high lands no longer existing in these parts. A few leaves of their annals are inscribed with forms of grotesque life, and stirring activities, which are there to attest the majesty of their revolutions. Geology, in little more than twenty years, has made the discovery, collected the facts, arranged and systematized the knowledge of the character and habits of the successive generations whose