in their destruction, a great part of our present coal fields, and many strata of the carboniferous order contain subordinate beds of a rich argillaceous iron ore. "A formation," adds our author, "that is at once the vehicle of two such valuable mineral productions as coal and iron, assumes a place of the first importance among the sources of benefit to mankind; and this benefit is the direct result of physical changes which affected the earth at those remote periods of time, when the first forms of vegetable life appeared upon its surface."

Resting on the transition rocks, and therefore believed immediately to succeed them in the era of their deposition, come the rocks of what has been called the Secondary epoch, during which, along with a distinct and peculiar vegetation, animals have existed, chiefly the inhabitants of the waters, or saurian reptiles, of gigantic forms, partly marine, partly amphibious, and partly terrestrial; and, at the same period also, have lived mammalia of the marsupial order, and some testudinata and feathered tribes ; as, not only their petrified remains, but, what is still more remarkable, the marks of their footsteps on sandstone, have recently been found to testify. Dr. Buckland, in speaking of fossil Testudinata, says, "The remains of land tortoises have been more rarely observed in a fossil state. Cuvier mentions but two examples, and these in very recent formations, at Aix, and in the Isle of France. 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." In a foot note, he states that a discovery of fossil footmarks, similar to that made at Corncocklemuir, which was communicated by me, in 1828, to the Edinburgh Royal Society,* has recently been made in Saxony, at the village of Hessberg, near Hildburghausen, in several quarries of gray quartzose sandstone, alternating with beds of red sandstone, nearly of the same age with that of Dumfriesshire, of which notices have been given by Dr. Hohnbaum, Pro

*[See vol. xi. of their Transactions.-AM. ED.]

fessor Caup, and Dr. Sickler. In another place, he also mentions footmarks of several extinct species of birds, having lately been found by Professor Hitchcock, in the new red sandstone of the valley of the Connecticut, one of them of a species of enormous dimensions, which took a stride of six feet.

[Professor Hitchcock's account of his discoveries was presented to the public through the American Journal of Science and the Arts, and may be found in vol. xxix., article Ornithichnology; a word derived from the Greek, signifying stony birdtracks. The Professor gives an interesting description of the footmarks, accompanied with illustrative drawings, among which is one representing the foot of the gigantic bird just alluded to.

Of this, he says, "In one specimen, the claw is at least two inches long, and even then a part of it appears to be missing. The whole length of the foot, consequently, is sixteen or seventeen inches! Length of the successive steps, between four and six feet! Indeed, I suspect, from the numerous examples which I have seen of tracks at the distance of four feet, that this was the ordinary step of the bird when walking; while it was able to lengthen it to six feet, when moving rapidly."

In speaking of another species, he observes, "The best specimen that I possess, exhibits, at a few inches. behind the heel, a depression nearly an inch deep, and several inches across; the anterior slopes to which, in the rear, appear as if large bristles had been impressed upon the mud. The impression extends backwards from the heel, at least eight or nine inches; so that the whole length of the track is not less than two feet! The rock on which this species of track appears, is composed of a fine blue mud, such as is now common in ponds and estuaries; and where the bird trod upon it, in some cases, it seems the mud was crowded upwards, forming a ridge around the track in front, several inches in height. Indeed, I hesitate not to say, that the impression made on the mud appears to have been almost as deep, indicating. a pressure almost as great, as if an elephant had passed over it. I could not persuade myself, until the evidence

became perfectly irresistible, that I was examining merely the track of a bird."

"As to their real size," he continues, "we may for ever be left to conjectures. But I am not sure that a practised comparative anatomist could not determine the size of a bird, having the size of the foot, and the length of the step given. I shall not attempt the problem any further than to state one fact, by way of comparison. The African ostrich, the largest of known birds, has a foot only ten inches long, reckoning from the back part of the heel to the extremity of the claw; the length of the leg, from the hip joint to the ground, is four feet one inch; and yet it sometimes weighs eighty or one hundred pounds, and, in walking, its head is as high as that of a man on horseback; or from seven to nine feet. May we not infer that some of these ancient birds, must have been almost twice as high and heavy as the ostrich ? From a few trials, I do not believe that the legs of a bird, (including the thigh,) whose ordinary step was four feet, could have been much less than six feet,"and"I should say his head must have been elevated from twelve to fifteen feet above the ground!"

"Such," says the Professor, "must have been the feathered tenants, that once occupied the now delightful valley of the Connecticut. At that time, we have every reason to believe that valley to have been an estuary; for the organic remains of the new red sandstone, are chiefly marine. And to show that other organic beings, that were contemporaries with these huge birds, were their compeers in size, I would mention a seafern, found in the new red sandstone of West Springfield, that has been uncovered, without reaching its limits, eighteen feet in length, and four feet in width! Indeed, the colossal bulk of these birds, is in perfect accordance with the early history of organic life in every part of our globe. The much higher temperature that then prevailed, seems to have been favorable to a giantlike developement of every form of life. The most interesting aspect, in which the facts that have been stated present themselves to the geologist, is, as to the evidence they afford of the very early

existence of birds, among the inhabitants of our globe. Heretofore, there has been no proof of their existence, until within a comparatively recent period. But it now appears that they were among the earliest of the vertebral animals that were placed on the globe. The discovery of some monument, that reveals the history of a people, a few hundred years earlier than had before been known, affords a high gratification to the antiquary. But in these simple footmarks, the existence, and some of the habits, of an interesting class of animals is proved, at a period so remote, that the entire population of the globe has since been changed, at least once or twice, and probably several times more. The number of years that have since elapsed, we cannot even conjecture, for, in respect to all the races of animals and plants that have occupied the globe, previous to the existing tribes, the Scriptures are silent, giving us to understand merely that a period of indefinite duration intervened, between 'the beginning' and the creation of man; and geological monuments, although they clearly point out successive epochs in the natural history of the globe, yet furnish us with few chronological dates."

Our limits will not allow of our making any further extracts from this long and valuable paper. We would refer those desirous of pursuing the investigation to the original document, and also to additional communications on the subject, to be found in subsequent volumes of the same periodical.-AM. EDITOR.]

On the subject of these discoveries, with particular allusion to that in Corncocklemuir, Dr. Buckland has the following elegant observations. The historian or the antiquary 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 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-fin

ished 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.”

To the secondary period, again, is believed to have succeeded another epoch, during which, rocks, of what is called the Tertiary formation, have been deposited, and animals, as well as plants, of a larger and more perfect kind, and approaching nearer to those of our own era, have existed.

The Tertiary epoch has recently been divided into four periods, founded on the proportions which their fossil shells bear to marine shells of existing species. During the first period, these productions exhibit but a small resemblance to our present orders; but this resemblance increases through each successive period, till the greater proportion of the fossil species come to bear a distinctly marked affinity to present existences. A similar remark may be made with regard to the inhabitants of the land. By far the greater proportion of the genera which existed during the earliest period of this epoch, are now extinct, while the terrestrial animals of the latest period have very generally antitypes in the living species of our own era. "It appears," says Dr. Buckland, "that, at this epoch, the whole surface of Europe was densely peopled by various orders of Mammalia; that the numbers of the herbivora were maintained in due proportion by the controlling influence of carnivora; and that the individuals of every species were con