4. The Stonesfield strata belong to the lower division of the great oolite. The slate of the district has been long known and prized for roofing purposes. The village of Stonesfield lies about twelve miles to the north-west of Oxford, beautifully situated on the brow of a valley, both sides of which have been deeply excavated for the extraction of the slate. Woodstock and Blenheim are both in the vicinity, neither of whose remarkable heroes ever dreamed of the mighty wars, waged in a far distant age from their own, by the fierce assailants whose remains have now been disturbed by these operations. Here are abundant the remains of palms, aborescent ferns, seed-vessels, leaves, stems of several genera of coniferæ, and traces of reeds and grasses. Wings and their cases, the _elytra_ of beetles, and other relics of insects, are mingled with the teeth, scales, fin-bones, rays of fishes, in the greatest profusion. And here, on the site of this ancient menagerie or battle-field, are the only known vestiges of mammalian animals in the secondary formations. One set of these remains resembles the Wombat, a marsupial didelphys of New South Wales; the other remains indicate a small insectivorous mammal, the Amphitherium, with thirty teeth in the lower jaw. Australia, therefore, supposed to furnish evidence of an entirely new order of things, has been long anticipated in all its types of plants and animals by the denizens of our own land—our waters swarming with cestraceonts, trigoniæ, and terebratulæ—and our fields clothed with araucariæ and cycadeous plants—when perhaps but little of that continent rose above the waters. 5. The DINOSAURIA constitute a tribe or sub-order of the lacertians, characterized by the large development of the sacrum, the dorsal vertebræ, the bones of the extremities, which are all provided with large medullary cavities. Of this tribe there are three well established genera—the Megalosaurus, the Hylæosaurus, and the Iguanodon. These were the gigantic crocodile lizards of the dry land, whose peculiarities of osteological structure distinguish them as clearly from the modern terrestrial and amphibious sauria, as the opposite modifications for an aquatic life, characterize the extinct enaliosauria, or marine lizards. The Dinosaurians belong properly to the Wealden fresh water formations, which may be regarded as the true habitat of this order of terrestrial fossil reptiles.