inches across. The jaws are long and furnished with sharp conical teeth, resembling those of the crocodile, and like them replaced continually, as they become worn, by new ones; the fins or paddles were four. Both these remarkable animals, now entirely extinct, are figured in the frontispiece of the present volume, which is designed to represent the condition of our globe during the period we are now considering.

Above the lias shales is a deposit which seems to indicate great changes in the organic world, caused by the elevation of wide tracts of country over certain portions of the globe, attended with numerous depressions in other parts, and the strata deposited during these movements seems to have formed the bed or final depository of many successive races of beings. The name Oolite given to this group of deposits signifies egg-like stone, because it is formed of small egg-like grains, like those comprising the roe of a fish, the nucleus of which, on microscopic examination, appears to be some minute organic substance, usually a fragment of coral, or a shell. To this class belong the so-called Oxford and Kimmeredge clays, and the Jura limestone, since the mass of the Jura mountains in France is of the oolite formation. During this period, an immense number of marine animals flourished, most of which are now entirely extinct, among them are peculiar corals, star-fishes, and sea-eggs or echini. Below we give a representation of a very perfect crustacean, similar to the

The fossil

lobster, from the oolite clay of Yorkshire, England. remains of insects are also common in these strata, and very peculiar and beautiful forms of ammonite, which seems to have

been most perfectly developed in the lias seas. We have before described a cephalapod called the orthoceratite, (page 306), subsequently we find this animal displaced by one with a curved and somewhat angular shell during the carboniferous formation, still later during the deposition of the lias and oolitic beds, we find another change under the form of the ammonite; at the same time the nautilus, a well known cephalapodous animal, closely related to the ammonite, was likewise abundant. The nautilus - still inhabits our tropical seas, and unfolds its fleshy sails to the gentle breezes, but long since the ammonite has been extinct. Another of the same class or group of animals, and which is now represented by the cuttle-fish, is the animal of the belemnite. The fossil called the belemnite from its resemblance to a dart or javelin, is not uncommon, and is found of various lengths and is

2

sometimes called by the singular names of the devil's toe-nail, thunderbolt, &c.; the general appearance of the fossil is however as represented in fig. 1, and perhaps no organic remains have ever caused more ludicrous mistakes, or given rise to more fanciful theories. It is the internal skeleton of an animal very much like the cuttle-fish, and represented in fig. 2. From the fossil remains, this animal appears to have been exceedingly large and formidable, preying upon the smaller fishes and reptiles, it was furished with eight long arms, each provided with from fifteen to twenty hooks; the eyes were large and the jaws powerful. Like the common squid, it seems to have been provided with an ovál sac, containing a dark fluid, ejected by the animal when alarmed in order to discolor the water and facilitate its escape. During

this period the plesiosaurus, and the ichthyosaurus abounded, and in addition we find another marine monster rivaling the largest whales in size, possessing webbed feet armed with strong claws.

The flora of the carboniferous period, we have observed, consisted mostly of ferns, and large coniferous trees, of gigantic di-, mensions, and of calamites, and numerous other plants the exact nature of which is not yet determined; but in the lias and oolitic formations an entirely new race of plants covered the earth. The ferns, which formerly constituted two-thirds of the entire species known, were greatly diminished, and the calamites and palms all disappear. Coniferous plants were still very common, but of different species from those of the earlier epochs, and plants analagous to the Cycadea and Zamias of the tropical regions seem to have replaced the ferns. The wood cut will give a tolerable idea of the character and appearance of the flora of

the oolitic period. During this Age of Reptiles, as it has been termed, one of the most marvellous beings, and which for a long time caused no little speculation and discussion among philosophers, flourished in considerable numbers. It has been termed the Pterodactyle, or wing-toed animal. (See next figure). This flying reptile, possessing the head of a bird, the wings of a bat, and the body and tail of an ordinary mammalian, appears to be a

sort of connecting link between the three great groups, reptiles,

birds, and mammals. It seems to have been capable of walking with ease upon the ground, of perching on trees, and of flying swiftly through the air. The teeth of the pterodactyle are long, pointed, and slender, from twenty to thirty in each jaw, and like the crocodile replaced by new ones when worn.- While the calcareous oolitic beds were being deposited in the sea, there seems to have been in some parts of the world, but particularly in the southern part of England, immense rivers, with extensive estuaries flowing over vast tracts of countries, and bearing down upon their waters and imbedding in the mud and silt of the shoaling estuaries, the remains of land plants and animals, and fresh water shells. To the beds or deposits thus made, the name Wealden has been given, (see page 188). With the exception of the plants of the coal epoch, this deposit is almost the sole evidence of the ancient land and its inhabitants. It is somewhat remarkable that among all the previous deposits no trace of any true quadruped has been found, all the remains belong to marine or land reptiles, and up to the time of the Wealden formation no traces except the few tracks on the new red sandstone, are found of birds. Dr. Mantell, who has so successfully investigated the geology of the south-east of England, has however in the latter named strata, discovered many fragments of bones supposed to

belong to birds allied the Heron. Among the reptiles characteristic of this deposit the most remarkable is the Iguanodon, so called from the resemblance of its teeth to those of the Iguana, a recent West Indian lizard. This gigantic suarian, or lizard, was upwards of 70 feet in extreme length; the circumference of body 14 feet; length of tail 523 feet; and of the hind foot 6 feet. In the British Museum, is a thigh bone of an Iguanodon, which is 3 feet in length, and eight inches in diameter. We cannot easily

conceive of a reptile of such huge dimensions; surpassing in height the tallest elephants, and far greater in bulk than any known living animal. A reptile of the same class, called the Hylæosaurus, or lizard of the Weald, was likewise discovered by Dr. Mantell; in dimensions it was somewhat less than the iguanodon, and armed with a row of spiral protuberances, and scaly plates.

During the deposit of the chalk, a vast multitude of fishes swarmed in the waters, among these were immense sharks, whose remains are plentifully found. How different the scenes then enacted, both on land and in the sea, from now. While upon the land, gigantic reptiles prowled through the dark woods, or along the chalky shores, covered with alligators and turtles; and the pterodactyle glided swiftly amid the dark foliage in pursuit of its prey; the icthyosaur, the plesiosaur, and voracious sharks roamed through the deep, devouring multitudes of smaller animals. Upon the surface of the waters, the nautilus and ammonite still sailed, and the sea egg rolled over the smooth bottom. Then, as now, the coral insect toiled on, and thousands of encrinites waved their flexile stems in the heaving waters Scenes like these, for ages, were witnessed upon the face of our planet, but we cannot begin to estimate the lapse, not of years or centuries, but of myriads, ere the change came which swept them forever from among the living things of earth, entombing them for memorials of those remote ages, which should tell in language too plain to be misunderstood, that many times, since the earth first commenced its revolution around the sun, changes have passed over its surface which would be more than sufficient to sweep away every living thing which now moves upon it.