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 araucaria 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.

The Megalosaurus was first described by Cuvier, and the family determined; he calculated the dimensions of the animal at from forty to fifty feet in length. Professor Owen, from better preserved specimens, has reduced it to thirty feet long: the head is five feet, the length of trunk with sacrum thirteen feet, and the tail about the same, allowing the Megalosaur to have had the same number of caudal vertebræ as the crocodile. The sacrum consisted of five anchylosed vertebræ, new in saurian anatomy: the hind-legs measure two yards, a metatarsal bone thirteen inches; the teeth are of corresponding dimensions, and curve backward in the form of a pruning-knife. The structure of the jaw indicates a long projecting snout, while the curvature of the teeth fitted them to retain like barbs the prey which they had once penetrated. All the organs of the monster declare the Megalosaur to have been a land animal, of carnivorous propensities, and in all probability performed, as headsman the same office upon the smaller herd of reptiles, sometimes making a snatch at a Plesiosaur, as both in turn did upon fishes and crusThe sport of an Indian jungle is child's play compared to the onslaught of these grim kings amidst their ancient pre

taceans.

serves. The remains occur in the deposits at Malton in Yorkshire, Cuckfield in Sussex, Bath, the Purbeck limestone, Tilgate Forest, and the Wealden.

The next genus of the land reptiles was remarkable for the size of the horny plates by which the body was protected. This is the Hylæosaurus-that is, forest-reptile-about twenty-five feet long, and covered with a series of large, flat, and pointed bones. These vary in length from five to seventeen inches, and are from three to seven and a half inches in breadth. In addition, as showing the kind of warfare to which he was exposed, a ridge of thick thorny scales pass along the back, and form an enormous dermal fringe, like the spines on the back of the living iguana tribes. The skeleton of the Hylæosaur has been found nearly entire, and all the parts in almost natural juxtaposition. The Wealden of Tilgate Forest, the deposits at Bolney and Battle of the same formation, contain the remains in considerable abundance.

What shall be said of the next figure that crosses the tragic stage, during this age of tyrant prodigies? The Iguanodon—a gigantic herbivorous lizard—is related to a family of harmless creatures (Iguana), which swarm in the West Indies, and in all the tropical forests of America, in certain peculiarities of the teeth greatly differing from those of other reptiles. The largest of living Iguanas, do not exceed five feet in length: the extinct genus attained a longitude of upward of twenty-eight to thirty feet. The caudal member was about thirteen, head three, trunk with sacrum twelve, and the girth of the body about fifteen feet. The teeth resemble the teeth of the rhinoceros as to bulk and general appearance, and, consisting as they do of incisors and molars, were recognized to belong to the order of herbivorous quadrupeds. The thigh-bone exceeds that of the largest-sized elephant, being from four to five feet in height, and presenting a circumference of nearly two feet in its smallest part. This animal, at its first discovery, was supposed to have attained the exaggerated proportions of nearly a hundred feet in length. But even under the reduced dimensions and more accurate deductions of Professor Owen, confirmed by those of Dr. Mantell, there is

still size sufficient, as well as peculiarities of structure, to lead us to regard it as one of the wonders of geology. One femur of a recently-discovered Iguanodon is twenty-seven inches in circumference, and must have been nearly five feet in length; and a tibia, found with the same, is four feet long. Dr. Melville has established the important physiological fact, that the cervical and anterior dorsal vertebræ were convexo-concave, that is,

convex in front and concave behind, as in the existing pachyderms; while the reverse form, the concavo-convex, predominates in the existing crocodilians and lizards. It is farther established, that in the Iguanodon, as in many fossil and recent reptiles, the anterior extremities were much shorter and less bulky than the posterior. As in the existing family, so in the extinct, the huge body was ornamented with a horn of bone which projected from the nose. This nasal organ seems to have been worn more for decoration than for use; unless, perhaps, to assist in perforating its way through the thickets of vegetation on which it subsisted, to push aside an unwelcome intruder upon his pasturage, or as a mere set-off against the unprecedented length of tail. Imagine a herd of these monsters feeding in a prairie—the denizens of a period when all things partook of the gigantic! "The concur rence of peculiarities so remarkable," says Buckland, as the union of this nasal horn with a mode of dentition of which there is no example, except in the Iguanas, affords one of the many proofs of the universality of the laws of co-existence, which prevailed no less constantly throughout the extinct genera and species of the fossil world, than they do among the living members of the animal kingdom." Professor Owen writes-" No reptile now exists which combines a complicated and thecodont dentition with limbs so proportionally large and strong, having such well-developed marrow-bones, and sustaining the weight of the trunk by sychondrosis or anchylosis to so long and complicated a sacrum, as in the order Dinosauria. The Megalosaurus and Iguanodons, rejoicing in these undeniably most perfect modifications of the reptilian type, attained the greatest bulk, and must have played the most conspicuous parts, in their respective characters as devourers of animals and feeders upon vegetables, that this earth has ever wit

nessed in oviparous and cold-blooded creatures.

They were as

superior in organization and in bulk to the crocodiles that preceded them as to those which came after them."

6. We close our enumeration of these fossils by simply stating, that the CROCODILIANS also flourished at this period. The living species are twelve in number, all remarkable for the size of their mouth, and their exuberant abundance of teeth. The extinct species were nearly as numerous, but all more allied to the gavials of New Holland than to the other members of the family. They seem chiefly to have subsisted on fishes, while their modern congeners are furnished with powers which enable them to prey upon mammalia and other quadrupeds. When Hobbes, the philosopher of Malmesbury-the old haunt of all these monsters— adopted the title "leviathan" for his political and anti-Christian views, he did it more in derision of the name than from any belief that such things as the term represents had ever or could ever have existed in rerum natura." Persons, even now, to whom the subject is presented for the first time, will turn with aversion from its details under the influence of the very opposite feelings from those of the infidel metaphysician. The evidence of facts however, will yield neither to prejudices nor to theories. And, while we dream not of representing the patriarch of Uz as drawing his inferences from geology, still his mind was alive to convictions of the grandeur and diversity of the works of creation—to a sense of his own ignorance—and filled at the same time with awe and veneration at the unsearchable wisdom of the ways of Providence. "STAND STILL AND CONSIDER THE WONDROUS WORKS OF GOD. HAST THOU ENTERED INTO THE SPRINGS OF THE SEA? HAST THOU PERCEIVED THE BREADTH OF THE EARTH? DECLARE, IF

THOU KNOWEST IT ALL."

CHAPTER IV.

THE WEALDEN FORMATION

THE Wealden formation is more local than any of the deposits we have yet considered. The term has a particular reference to the district features of Kent, Surrey, Sussex, and Hampshire, known as the Wolds, from the German wald, signifying a wood or forest and as the geological position of the group is in immediate superior connection with the oolites, and inferior to the chalk, the character and history of the Wealden fall to be given in this place. The Speeton clay of Yorkshire, displayed along the cliffs adjoining Filey Bay, is considered to belong to the same series as the gault or blue and gray marls of Cambridge, Kent and Sussex; but it contains some characteristic indications of the Kimmeridge clay, and, therefore, we should expect that, in Yorkshire, these two strata are not separated as in the south of England.

I. NATURE AND EXTENT OF THE DEPOSIT. The Wealden is a fresh water or estuary formation, as is clearly established by its fossils as well as by its lithology. The group consists of layers of clay, sand, shale, with subordinate beds of limestone, grit, and friable sandstone. The Hastings sands, Tilgate Forest beds, Tunbridge Wells deposits, and the Ashburn lignite shales and ferruginous sands, are all constituents of the series. The Dover Railway traverses the formation between Red Hill and Ashford: the branch leading to Tunbridge Wells affords excellent sections of the clay and sands. Thus occupying, in an irregular triangular form, the south-east of England, the wealden again emerges in the principality of Hanover, and other places in the north of Germany continuing in the same course, it is again found on the British shores, occurring at Linksfield, near Elgin.