Buckland's Bridgewater Treatise a table is given, exhibiting the animals found at Darmstadt in a bed of sand referrible to the Miocene period. In this list are mentioned two skeletons of the dinotherium (represented in the vignette to this tract), a large herbivorous animal, called by Cuvier the Gigantic Tapir; two large tapirs; calicotherium, two large tapir-like animals of this name; two rhinoceroses; hippotherium, an animal allied to the horse; three hogs; four large cats, some as large as a tiger; the creature called the Glutton; agnotherium, allied to the dog; and machairodus, an animal allied to the bear. From this list the reader will perceive the gradual approach in the Miocene animals to existing species. The largest of the terrestrial mammalia yet discovered belongs to the period now under notice; it is the dinotherium, or gigantic tapir, already mentioned. No complete skeleton has yet been discovered; but from the bones found, Cuvier and others imagine the animal to have reached the extraordinary length of eighteen feet. The most remarkable peculiarities of its structure consist in two enormous tusks at the end of its lower jaw, and in the shoulder-blade, which resembles that of a mole, and is calculated to have given the power of digging, or other free movement, to the fore-foot. It seems probable that this stupendous creature lived in fresh-water lakes, and had the half-terrestrial half-aquatic habits of the walrus or riverhorse. The tusks might be used in digging up roots and plants, and also in sustaining the head on banks during sleep, or in pulling the body out of the water, as the walrus uses a similar pair of tusks. 'In these characters,' says Buckland, 'of this gigantic, herbivorous, aquatic quadruped, we recognise adaptations to the lacustrine (lakecovered) condition of the earth, during that portion of the Tertiary periods to which the existence of these seemingly anomalous creatures seems to have been limited.'

In the Miocene period, the seas became the habitation of numbers of marine mammalia, consisting of dolphins, whales, seals, walrus, and the lamantin, or manati. Few of these animals were of the same species as those which exist at present, but the differences were far from being great or remarkable. This circumstance, as well as the considerable number of fossil shells identical with existing ones, exhibits an approach in the character and tenantry of the Miocene seas to the present state of things in these respects. The discovery, also, of true terrestrial mammalia, as the rhinoceros and hog, in the Miocene formations, shews that, since the era of the gigantic reptiles, no slight portion of the earth's surface had assumed the condition of dry land, fit for the support of the common herbivora.

THE MASTODON, MEGATHERIUM, ETC.

It now remains to inquire into the nature and peculiarities of the animals characterising the Pliocene age, which, for convenience, has

been arranged into two periods, the Older and Newer Pliocene, the latter of which immediately preceded the formation of the diluvial layer constituting the present superficial matter of the globe. Whereas only eighteen in the hundred of the Miocene shells were of recent species, in the Older Pliocene from thirty-five to fifty, and in the Newer Pliocene not less than from ninety to ninety-five in the hundred, are identical with shells of existing species. This great change is accompanied by the disappearance of the Palæotherian family and others, which formed the most striking animals in the periods immediately preceding. In place of these extinct species of extinct Pachydermatous or thick-skinned families, we observe in the strata of the Pliocene periods a vast number of remains of existing Pachydermatous families, such as the elephant, the rhinoceros, and the hippopotamus, though these remains belong to varieties that are now extinct. The first traces also now appear of Ruminant animals-of oxen, deer, camels, and other creatures of the same class.

The enormous creature called the Great Mastodon, belonging to the Pliocene era, was the largest of all the fossil animals whose skeletons have been found complete, or nearly so. Much confusion has existed relative to this animal's true character, many naturalists regarding it as an extinct species of the elephant, and others holding that it approached nearer to the hippopotamus. Cuvier, however, determined it to be the head of a distinct family, comprehending several other species. It is about one hundred and twenty years since remains of the mastodon were first discovered in America, and vast quantities of them have been since found in the same region, buried chiefly in marshy grounds. One skeleton, nearly complete, was dug up on the banks of the Hudson in 1801, and it is from this that a correct knowledge of the animal has been principally derived. In height, the mastodon seems to have been about twelve feet, a stature which the Indian elephant occasionally attains. But the body of the mastodon was greatly elongated in comparison with the elephant's, and its limbs were thicker. The whole arrangement of the bony structure resembled that of the elephant, excepting in one point, which Cuvier regarded as of sufficient consequence to constitute the mastodon a different genus. This was the cheek-teeth, which are divided, on their upper surface, into a number of rounded, obtuse prominences, arranged not like the elephant's but like those of the wild boar and hippopotamus; whence it is concluded, that, like the latter animals, the mastodon must have lived on tender vegetables, roots, and aquatic plants, and could not have been carnivorous. The lower jaw of a skeleton found on the Hudson is two feet ten inches in length, and weighs sixty-three pounds. Like the elephant, the mastodon had two tusks, curving upwards, and formed of ivory, and, in the opinion of Cuvier, it had also a trunk of the same kind with the former animal's.

Another creature, belonging to the later Pliocene ages, if not indeed

to the era of the Diluvial formation, has been discovered in America, both north and south. This is the Megatherium, an animal more widely removed in character from any existing creature, than any of the other fossil remains that have been yet observed. The megatherium was discovered towards the end of the last century. A skeleton, almost entire, was found nearly at one hundred feet of depth, in

excavations made on the banks of the river Luxan, several leagues to the south-west of Buenos Ayres. The megatherium was a tardigrade (slow-moving) animal, like the sloth, and was at least the size of a common ox. Its limbs were terminated by five thick toes, attached to a series of huge flat metatarsal bones, or those bones with which the toes are continuous as in the human foot. Some of the toes,' 'says Buckland, in his notice of this creature,' are terminated by large and powerful claws of great length; the bones supporting these

claws are composed partly of an axis, or pointed core, which filled the internal cavity of the horny claw; and partly of a bony sheath, that formed a strong case to receive and support its base.' These claws, from their position, were admirably calculated for the purpose of digging. The legs of this creature were of enormous thickness, its thigh-bone being nearly three times the thickness of the same bone in the elephant. The other bones of the megatherium were almost proportionably heavy. A still more remarkable feature, however, in the animal's structure, was the coat of armour, of solid bone, varying from three-fourths of an inch to an inch and a half in thickness, which covered its hide, in the same manner as the armadillo's is encased by the same substance.

The habits and peculiarities of this stupendous sloth-for so the megatherium may be termed are well described and explained in Dr Buckland's Bridgewater Treatise. After stating that with the head and shoulders of a sloth, it combined, in its legs and feet, an admixture of the characters of the ant-cater and the armadillo, and resembled them still more in being cased in a coat of armour, he continues: 'Its haunches were more than five feet wide, and its body twelve feet long and eight feet high; its feet were a yard in length, and terminated by most gigantic claws; its tail was probably clad in armour, and much larger than the tail of any other beast among living or extinct terrestrial mammalia. Thus heavily constructed, and ponderously accoutred, it could neither run, nor leap, nor climb, nor burrow under the ground, and in all its movements must have been necessarily slow; but what need of rapid locomotion to an animal whose occupation of digging roots for food was almost stationary?—and what need of speed for flight from foes to a creature whose giant carcass was encased in an impenetrable cuirass, and who by a single pat of his paw, or lash of his tail, could in an instant have demolished the cougar or the crocodile? Secure within the panoply of his bony armour, where was the enemy that would dare encounter this behemoth of the Pampas (the South American region where it existed), or in what more powerful creature can we find the cause that has effected the extirpation of his race?

'His entire frame was an apparatus of colossal mechanism, adapted exactly to the work it had to do; strong and ponderous, in proportion as this work was heavy, and calculated to be the vehicle of life and enjoyment to a gigantic race of quadrupeds; which, though they have ceased to be counted among the living inhabitants of our planet, have, in their fossil bones, left behind them imperishable monuments of the consummate skill with which they were constructed.'

Another extinct tardigrade creature, presenting many of the characters of the megatherium, was discovered in a calcareous cavern in Virginia, and received from President Jefferson, who first described some of its bones, the name of the Megalonyx. Jefferson conceived the claw to be that of an extinct feline animal of vast size (that is to

say, an animal of the same description as the tiger, lion, cat, and lynx, all of which are beasts of prey); but the French naturalist declared the possessor of the claw to have been herbivorous, or calculated to live on herbs; and this was triumphantly proved by the discovery of others of its bones. The megalonyx appears (for a complete skeleton has not yet been found) to have been a little smaller in size than the megatherium. But the megalonyx, according to Cuvier, was herbivorous, after the manner of the sloth, since its teeth were conformed precisely like that animal's. From the resemblance of their feet also, he concludes that their gait was similar, and all their movements alike. The difference in volume of body, however, must have prevented the habits of the megalonyx from being perfectly analogous to those of the sloth. The megalonyx could but seldom have climbed up trees, because it must rarely have found any sufficiently strong to support its weight. But its height would enable it to browse, like the sloth, among the leaves of trees, without its being under the necessity of climbing any but such tall and strong ones as could bear its weight. It is even possible that the weight and strength of the creature may have been serviceable in bending down, and perhaps in overturning trees, the branches of which contained its food.

The next fossil animal to which we shall refer, is that long called the Mammoth, under the impression that it was a distinct genus, but which is now universally denominated the Fossil Elephant, as being an extinct species of that existing family. The mammoth (which name we shall retain for the sake of distinction) is rather to be regarded as a creature of the Diluvial than of the Pliocene period (that is to say, belonging to the age when, by means of floods, the present beds of gravel and hard clay, so often found between the rocks and vegetable soil, were laid down upon the earth), as some specimens have been discovered in Siberia, with portions of the flesh and hair actually preserved along with the bones among the ice. It was at first thought, when numbers of mammoth bones were discovered in Italy, and other southern countries of Europe, that they were the remains of elephants brought by the Romans and others from Asia and Africa; but the incalculable quantities of them ultimately detected in Russia and other districts, where elephants were never brought in the shape of oriental tribute as they were to Rome, shewed that their presence was to be attributed to natural causes, and not to the casual agency of man. In truth, the beds of the Volga, Don, and other northern rivers, are filled with them, and this can be accounted for only on the hypothesis, either of an alteration in the habits of the elephant, or of a great change of climate in these parts, or of some immense moving force on the face of the earth, which has carried them thither. The instance in which part of the flesh was found along with the bones, will supply us with a general description of the mammoth. When the animal, on this occasion, was first seen through