perhaps the most remarkable of them all, viz. the P. Dolichodeirus." -p. 203. We cannot have a better account of its habits than that which Conybeare, who first discovered the genus, has put on record in the Transactions of the Geological Society of London: "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 the 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 sea-weed, and raising its nostrils to a level with the surface from a considerable depth, may have found a secure retreat from the assaults 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.'-pp. 211, 212. Dr. Buckland thus concludes his notice of these most interesting animals : Pursuing the analogies of construction that connect the existing inhabitants of the earth with those extinct genera and species which preceded the creation of our race, we find an unbroken chain of affinities pervading the entire series of organized beings, and connecting all past and present forms of animal existence by close and harmonious ties. Even our own bodies, and some of their most important organs, are brought into close and direct comparison with those of reptiles, which, at first sight, appear the most monstrous productions of creation; and in the very hand and fingers with which we write their history we recognise the type of the paddles of the ichthyosaurus and plesiosaurus. Extending a similar comparison through the four great classes of vertebral animals, we find in each species a varied adaptation of analogous parts to the different circumstances and conditions in which it was intended to be placed. Ascending from the lower orders, we trace a gradual advancement in structure and office, till we arrive at those whose functions are the most exalted: thus, the fin of the fish becomes the paddle of the reptile plesiosaurus and ichthyosaurus; the same organ is converted into the wing of the pterodactyle, the bird and and bat; it becomes the fore-foot, or paw, in quadrupeds that move upon the land, and attains its highest consummation in the arm and hand of rational man. . . . "Usque adeo natura, una eadem semper atque multiplex, disparibus etiam formis effectus pares, admirabili quadam varietatum simplicitate, conciliat."-pp. 213, 214. After a concise but well-digested history of the mososaurus, or great marine animal of Maestricht, most nearly allied to the monitors (monitory lizards) of modern times, though infinitely gigantic in comparison;-an animal which appears to have been introduced during the deposition of the chalk to take the places of the then extinct ichthyosauri and plesiosauri that, from the lias upwards, held their sway over the ocean, and to have been destined in its turn to make room for the cetacea (whales) of the tertiary period; we are thus introduced to the pterodactyle: 'Among the most remarkable disclosures made by the researches of geology, we may rank the flying reptiles, which have been ranged by Cuvier under the genus pterodactyle; a genus presenting more singular combinations of form than we find in any other creatures yet discovered amid the ruins of the ancient earth. The structure of these animals is so exceedingly anomalous that the first discovered pterodactyle was considered by one naturalist to be a bird, by another as a species of bat, and by a third as a flying reptile. This extraordinary discordance of opinion respecting a creature whose skeleton was almost entire, arose from the presence of characters apparently belonging to each of the three classes to which it was referred;-the form of its head, and length of neck, resembling that of birds, its wings approaching to the proportion and form of those of bats, and the body and tail approximating to those of ordinary mammalia. These characters, connected with a small skull, as is usual among reptiles, and a beak furnished with not less than sixty pointed teeth, presented a combination of apparent anomalies which it was reserved for the genius of Cuvier to reconcile. In his hands this apparently monstrous production of the ancient world has been converted into one of the most beautiful examples yet afforded by comparative anatomy, of the harmony that pervades all nature, in the adaptation of the same parts of the frame to infinitely varied conditions of existence. 'We are already acquainted with eight species of this genus, varying from the size of a snipe to that of a cormorant. In external form these animals somewhat resemble our modern bats and vampires: most of them had the nose elongated, like the snout of a crocodile, and armed with conical teeth. Their eyes were of enormous size, apparently enabling them to fly by night. From their wings projected fingers, terminated by long hooks, like the curved claw on the thumb of the bat. These must have formed a powerful paw, where with the animal was enabled to creep or climb, or suspend itself from trees. It is probable, also, that the pterodactyles had the power of swimming, which is so common in reptiles, and which is now possessed by the E 2 vampire vampire bat of the island of Bonin. Thus, like Milton's fiend, qualified for all services and all elements, the creature was a fit companion for the kindred reptiles that swarmed in the seas, or crawled on the shores of a turbulent planet. "The fiend, O'er bog, or steep, through strait, rough, dense, or rare, With flocks of such-like creatures flying in the air, and shoals of no less monstrous ichthyosauri and plesiosauri swarming in the ocean, and gigantic crocodiles and tortoises crawling on the shores of the primeval lakes and rivers, air, sea, and land must have been strangely tenanted in these early periods of our infant world....... In the case of the pterodactyle we have an extinct genus of the order Saurians, in the class of reptiles, (a class that now moves only on land or in the water,) adapted by a peculiarity of structure to fly in the air. It will be interesting to see how the anterior extremity, which in the fore leg of the modern lizard and crocodiles is an organ of locomotion on land, became converted into a membraniferous wing; and how far the other parts of the body are modified so as to fit the entire animal machine for the functions of flight.'-pp. 221-225. We cannot afford space for the details of this inquiry, which is, however, full of interest, and, as in the instances already mentioned, affords striking proofs that, even in ages incalculably remote, the same care of a common Creator which we witness in the mechanism of our own bodies and those of the myriads of inferior creatures that move around us, was extended to the structure of creatures that at first sight seem made up only of monstrosities. Dr. Buckland next brings in review before us, those gigantic terrestrial lizards, the megalosaurus, iguanodon, and hylæosaurus, reptiles extending some of them to seventy feet in length. Among other instances of adaptation, the internal condition of their bones is shown to differ from that of the aquatic saurians :— In the ichthyosauri and plesiosauri, whose paddles were calculated exclusively to move in water, even the largest bones of the arms and legs were solid throughout. Their weight would in no way have embarrassed their action in the fluid medium they inhabited; but in the huge megalosaurus, and still more gigantic iguanodon, which are shown, by the character of their feet, to have been fitted to move on land, the larger bones of the legs were diminished in weight, by being internally hollow, and having their cavities filled with the light material of marrow, while their cylindrical form tended also to combine this lightness with strength.'-pp. 235, 236. The amphibious saurians, or crocodileans of the old world, were nearly similar in their structure to those of the present day. We must refer the reader to the work itself for a very interesting account of them, and pass on to the testudinata (tortoises), which bring immediately before us the interesting facts of fossil footsteps: 'Scotland has recently afforded evidence of the existence of more than one species of these terrestrial reptiles during the period of the new red or variegated sandstone formation. The nature of this evidence is almost unique in the history of organic remains. It is not uncommon to find on the surface of sandstone tracks which mark the passage of small crustacea and other marine animals whilst this stone was in a state of loose sand at the bottom of the sea. Laminated sandstones are also often disposed in minute undulations, precisely resembling those formed by the ripple of agitated water upon sand.' -[Such exactly as we see left by the receding tide on the sands of our coast.]-The same causes which have so commonly preserved these undulations would equally preserve any impressions that might happen to have been made on beds of sand by the feet of animals; the only essential condition of such preservation being that they should have become covered with a further deposit of earthy matter before they were obliterated by any succeeding agitations of the water. The impressions in Dumfries-shire traverse the rock in a direction either up or down, and not across the surfaces of the strata, which are now inclined at an angle of 38°. On one slab there are twenty-four continuous impressions of feet, forming a regular track, with six distinct repetitions of the mark of each foot, the fore-foot being differently shaped from the hind-foot; the marks of claws are also very distinct.' -pp. 258-261. The strata which bear these impressions lie on each other like volumes on the shelf of a library, when all inclining to one side: the quarry has been worked to the depth of forty-five feet from the top of the rock; throughout the whole of this depth similar impressions have been found, not on a single stratum only, but on many successive strata; i. e., after removing a large slab which contained footprints they found perhaps the very next stratum, at the distance of a few feet, or it might be less than an inch, exhibiting a similar phenomenon. Hence it follows that the process by which the impressions were made on the sand, and subsequently buried, was repeated at successive intervals.'-Note, p. 259. Dr. Buckland, by way of experiment, took soft sand, and clay, and unbaked pie-crust or paste. Upon these several substances he made living tortoises (Emys and Testudo Græca) walk; when he found the marks made by the animals sufficiently close to render it quite certain that the fossil footsteps were also impressed by the feet of tortoises. The historian or the antiquary,' he remarks, may have traversed the fields of ancient or of modern battles; and may have pursued the line of march of triumphant conquerors, whose armies trampled down the most mighty kingdoms of the world. The winds and storms have utterly obliterated the ephemeral impressions of their course. Not a track track remains of a single foot, or a single hoof, of all the countless millions of men and beasts whose progress spread desolation over the earth; but the reptiles, that crawled upon the half-finished surface of our infant planet, have left memorials of their passage, enduring and indelible. No history has recorded their creation or destruction; their very bones are found no more among the fossil relics of a former world. Centuries and thousands of years may have rolled away between the time in which these footsteps were impressed by tortoises upon the sands of their native Scotland, and the hour when they are again laid bare and exposed to our curious and admiring eyes. Yet we behold them stamped upon the rock, distinct as the track of the passing animal upon the recent snow; as if to show that thousands of years are but as nothing amidst eternity, and, as it were, in mockery of the fleeting perishable course of the mightiest potentates among mankind.'—pp. 262, 263. It is impossible to turn to the subject of fossil fishes without alluding to Professor Agassiz. Dr. Buckland has drawn largely from that distinguished ichthyologist; but as a sketch of his labours was introduced in our last Number,* we pass to our author's own striking remarks in concluding this branch of his subject: 'It results from the review here taken of the history of fossil fishes, that this important class of vertebrated animals presented its actual gradations of structure amongst the earliest inhabitants of our planet; and has ever performed the same important functions in the general economy of nature as those discharged by their living representatives in our modern seas, and lakes, and rivers. The great purpose of their existence seems at all times to have been to fill the waters with the largest possible amount of animal enjoyment. The sterility and solitude which have sometimes been attributed to the depths of the ocean exist only in the fictions of poetic fancy. The great mass of the water that covers nearly three-fourths of the globe is crowded with life, perhaps more abundantly than the air and the surface of the earth; and the bottom of the sea, within a certain depth accessible to light, swarms with countless hosts of worms, and creeping things, which represent the kindred families of low degree which crawl upon the land. 'The common object of creation seems ever to have been the infinite multiplication of life. As the basis of animal nutrition is laid in the vegetable kingdom, the bed of the ocean is not less beautifully clothed with submarine vegetation than the surface of the dry land with verdant herbs and stately forests. In both cases the undue increase of herbivorous tribes is controlled by the restraining influence of those which are carnivorous; and the common result is, and ever has been, the greatest possible amount of animal enjoyment to the greatest number of individuals.' *No. CX. p. 433. We |