the second six or seven, the third eight or nine, the fourth eight, and the fifth six phalanges. Professor Owen, who gives these numbers, adds that there can be little doubt that they were enveloped, like the paddles of Cetacea, in a common sheath of integument, and that, from the natural curve of the digits, the paddles of the Plesiosaur must have had a more elegant and tapering form, and have possessed greater flexibility than those of the modern whales.

The posterior or pelvic extremities almost always equal, and sometimes, as in Plesiosaurus macrocephalus, exceed the anterior extremity, but they closely correspond with them in their radiated appendages. The five metatarsals and their digits, Professor Owen observes, correspond in structure with those of the forepaddle. The first or tibial metatarsal, he tells us, supports three phalanges, the second five, the third eight or nine, the fourth eight, and the fifth six phalanges. The structure of the bones of this extremity indicates, in Professor Owen's opinion, that the hind paddle had a freer inflection forwards or upon the tibia, than in the opposite direction; and he thinks that it may have given a compound motion to the propelling stroke of the paddle, similar to that which in skilful rowing is termed "feathering the oar." He further remarks, that the articular extremities of the phalanges of both the fore and hind paddles are sub-concave, with an irregular surface, indicating that they were joined by ligaments or fibro-cartilage, and not by a synovial membrane.

But what were the habits of this chimera-like creature? The best answer will be given by the Rev. W. Conybeare, who thus infers those of Plesiosaurus dolichodeirus:

"That it was aquatic is evident from the form of its paddles; that it was marine is almost equally so, from the remains with which it is universally associated; that it may have occasionally visited the shore, the resemblance of its extremities to those of the turtle may lead us to conjecture; its motion, however, must have been very awkward on land; its long neck must have impeded its progress through the water; presenting a striking contrast to the organization which so admirably fits the Ichthyosaurus to cut through the waves. May it not therefore be concluded (since, in addition to these circumstances, its respiration must have required frequent access of air), that it swam upon or near the surface, arching back its long neck like a swan, and occasionally darting it down at the fish which happened to float within its reach. It may, perhaps, have lurked in shoal water along the coast, concealed among the seaweed, and raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assault of dangerous enemies; while the length and flexibility of its neck may have

compensated for the want of strength in its jaws, and its incapacity for swift motion through the water, by the suddenness and agility of the attack which they enabled it to make on every animal fitted for its prey, which came within its reach."

Professor Buckland is of opinion that the tail, being comparatively short, could not have been used like the tail of fishes, as an instrument of rapid impulsion in a forward direction; but was probably employed more as a rudder to steer the animal when swimming on the surface, or to elevate or depress it in ascending and descending through the water. The same consequence as to slowness of motion, would, he thinks also, follow from the elongation of the neck to so great a distance in front of the anterior paddles. The total number of vertebræ in the entire column was, he observes, about ninety. From all these circumstances, Dr. Buckland infers that this animal, although of considerable size, had to seek its food as well as its safety, chiefly by means of artifice and concealment.

No less than sixteen species are enumerated by Professor Owen, one described by Cuvier, two by Conybeare, and the rest by himself.

The period of existence of these enaliosaurians, extended through the whole of the oolitic range, including the lias and oolite of the Wealden and chalk formations. The chalk marl appears to be the most recent deposit where they have been found they occur also in the gault.

Their name was legion. To say nothing of the bones which testify to their numbers, the petrified remains of their digested food put the question of their numerical force out of doubt.

"On the shore at Lyme Regis," says Dr. Buckland, "these coprolites are so abundant, that they lie like potatoes scattered in the ground; still more common are they in the lias of the Estuary of the Severn, where they are similarly disposed in strata of many miles in extent, and mixed so abundantly with teeth and rolled fragments of the bones of reptiles and fishes, as to show that this. region, having been the bottom of an ancient sea, was for a long period the receptacle of the bones and focal remains of its inhabitants. The occurrence of coprolites is not, however, peculiar to the places just mentioned; they are found in greater or less abundance throughout the lias of England; they occur also in strata, of all ages, that contain the remains of carnivorous reptiles, and have been recognised in many and distant climates both of Europe and America."

The sea in which these extinct monsters gambolled, must have been not unlike that of the present day, especially in tropical climates. That the medium was capable of transmitting light in the same manner that sea-water now does, might be safely

inferred from such parts of the ocular apparatus of the fossil reptiles and fish as are still preserved to us, although the soft parts of the eye are, of course, absent. But in the Trilobites, those most ancient and extinct crustaceans which inhabited the bottom of the old seas, we have the eye itself petrified; and this, when compared with the similar compound eyes of the Serolis and Limulus, or King Crab, which now exist, proves, as Dr. Buckland has pointed out, that the visual organs of both were fashioned for media essentially the same, and entirely dispels the dream of those geologists who believed that a turbid chaotic fluid holding in solution the precipitates from which the earth's crust was deposited, then prevailed.

In the same sea wherein the Ichthyosaur and Plesiosaur took their pastime, swam shoals of the finny tribe, now extinct and potted in their ancient mud, among them the great Sauroid fishes, which must have almost disputed the mastery with some of the younger branches of the enaliosaurian families. Starfishes, or Ophiuri, not unlike those which at present occur on our shores; crinoideans, or stone-lilies as the collectors term them; and extinct crustaceans, organized, however, in the same manner as existing species, were present. Belemnites and Cornua Ammonis, which have left no living representative, and Orthocerata, with numerous other testaceous mollusca, were there, to say nothing of turtles; so that the ancient and respectable enaliosaurian corporation must have fared sumptuously; and, certainly the Ichthyosaurian branch of it had a more than aldermanic development of the mouth-and-stomach power.

The enaliosaurians, Professor Owen observes, are immediately connected with the crocodilian reptiles by the extinct and gigantic Pliosaurus, which is more closely allied to the true Saurians, and whose remains occur in the Kimmeridge and Oxford clays. The teeth are remarkable for their thickness and strength, and the cervical vertebræ for their shortness, the enormous jaws having been wielded by a neck, if neck it may be called, as short and strong as that of the whales.

But there were other sea-dragons besides the enaliosaurians, framed, however, upon a somewhat different principle, and according to the Lacertian type, such as the Mosasaurus or great animal of Maastricht.

This marine giant appears to have been most nearly allied to the Monitory lizards, as they are called, which now frequent the river-sides and marshy places in warm countries, and have had the credit, not very deservedly, we believe, of warning the traveller, by a peculiar whistling sound, of the approach of crocodiles and their congeners. Five feet is a great length for an existing Monitor to attain; but the Mosasaur must have reached

twenty-five feet. The noble head in the Paris Museum, of which we have casts in this country, is four feet long; that of a large existing Monitor does not measure more than five inches in length.

The fossil was found in the calcareous freestone, near Maastricht, the most recent deposit of the cretaceous formation, in company with Ammonites, Belemnites, and other organic remains of the chalk formation în 1780, and for some time adorned that city. But it was a very sphinx's riddle to be learned. Some thought it was an enormous crocodile; others would have it to be very like a whale; but at last Camper suggested, and Cuvier afterwards confirmed its true zoological relations.

Fancy a marine Monitor of the length and bulk of a Grampus, with four paddles instead of legs, and a high and deep oar-like tail formed for propelling the animal through the wave, instead of the long and slender tail of the living species-and you have some notion of the Mosasaur.

Its jaws and teeth were tremendous. Nothing comparable to them can be imagined, excepting the ancient caricature, which may be known to some of our readers, representing a learned gentleman in his robes, not quite at his ease, between a pair of Saurian jaws, worthy of Munchausen's creation, and underwritten,

`A LAWYER AND A SAWYER.

The rush of the Mosasaur through the water must have been most rapid; and its whole structure bespeaks an agent for keeping down the larger races of ancient fishes, more active and destructive than the great Ichthyosaur itself..

The Paris specimen belonged to the collection of Hoffman, from whom it was said to have been taken by the chapter of Maastricht, by virtue of some droits vested in them, and was given up by the Dean to the French army when it invested the city. Fortunate was the inhabitant whose dwelling lay near the place where the head of the Mosasaur was deposited: for the story goes, that to prevent the possibility of injury to a prize, which the besiegers were determined to possess, the French cannoniers were enjoined not to point their artillery towards that part of the city which held the remains of this grand SeaDragon.

ANCIENT AMPHIBIOUS AND TERRESTRIAL

DRAGONS,

Through many a dark and dreary vale

They passed, and many a region dolorous,

Rocks, caves, lakes, fens, bogs, dens, and shades of death."

PARADISE LOST.

Ir, with the eyes of the imagination aided by the lights afforded by the strata and the ancient inhabitants buried therein, we look back upon our earth when the forms of crocodilian reptiles first came upon it, we may picture to ourselves an oozy, spongy, reeky land, watered with wild rivers, and largely overspread by a vast expanse of lakes, on whose dreary, slimy banks gigantic crocodiles reposed amid enormous extinct bog-plants, or floated log-like in the fenny sunshine on their waters, while the silence of the desolate scene was broken by the clank of their monstrous jaws, as they ever and anon closed upon the bygone generations of fishes, or by the growlings and explosions of the distant volcano.

5

With, perhaps, one exception-the crocodile of the Ganges namely none of the ancient crocodilians exhibit specific identity with the alligators, crocodiles, and gavials now existing. And while they differ from the present races, the modifications of their osseous structure in which they so vary, as well as from each other, are much greater than any of those by which the skeletons of the existing species differ among themselves.

"Not only," says Professor Owen, "do the form and proportions of the peripheral parts, as of the jaws, the teeth, and the locomotive extremities vary, but the spine or central axis of the skeleton, offers modifications of the articular surfaces of the component vertebræ, which are quite unknown in the alligators, crocodiles, and gavials of the present epoch. In these existing species the anterior surface of the vertebral centrum is concave, the posterior convex, except in the atlas and sacrum. But besides this mode of junction, Cuvier has recognised in the crocodilians of the secondary formations two other types of vertebral structure: in one of these the positions of the ball and socket are