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-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.*

* A similar discovery of fossil footsteps 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 Dumfries. (See Pl. 26'. 26′′. 26′′".)

The following account of them is collected from notices by Dr. Hohnbaum and Professor Kaup. "The impressions of feet are partly hollow, and partly in relief; all the depressions are upon the upper surfaces of slabs of sandstone, whilst the reliefs are only upon the lower surfaces, covering those which bear the depressions. These reliefs are natural casts, formed in the subjacent footsteps as in moulds. On one slab (see Pl. 26',) six feet long by five feet wide, there occur many footsteps of more than one animal, and of various sizes. The larger impressions, which seem to be of the hind-foot are eight inches long, and five wide. (See Pl. 26′′.) One was twelve inches long. Near to each large footstep, and at the regular distance of an inch and a half before it, is a smaller print of a fore-foot, four inches long and

SECTION XIII.

FOSSIL FISH E S.

THE history of Fossil Fishes is the Branch of Palæology which has hitherto received least attention, in consequence of the imperfect state of our knowledge of existing

three inches wide. These footsteps follow one another in pairs, at intervals of fourteen inches from pair to pair, each pair being in the same line. Both large and small steps have the great toes alternately on the right and left side; each has the print of five toes, and the first, or great toe is bent inwards like a thumb. The fore and hind-foot are nearly similar in form, though they differ so greatly in size.

On the same slabs are other tracks, of smaller and differently shaped feet, armed with nails. Many of these (Pl. 26′) resemble the impressions on the sandstone of Dumfries, and are apparently the steps of Tortoises.

Professor Kaup has proposed the provisional name of Chirotherium for the great unknown animal that formed the larger footsteps, from the distant resemblance, both of the fore and hind-feet, to the impression of a human hand; and he conjectures that they may have been derived from some quad. ruped allied to the Marsupialia. The presence of two small fossil mammalia related to the Opossum, in the Oolite formation of Stonesfield, and the approximation of this order to the class of Reptiles, which has already been alluded to, (page 64, note,) are circumstances which give probability to such a conjecture. In the Kangaroo, the first toe of the fore-foot is set obliquely to the others, like a thumb, and the disproportion between the fore and hind feet is also very great.

A farther account of these footsteps has been published by Dr. Sickler, in a letter to Blumenbach, 1834. Our figure, (Pl. 26',) is copied from a plate that accompanies this letter; on comparing it with a large slab, covered with similar footmarks, from the same quarries, lately placed in the British Museum, (1835) I find that the representations, both of the large and small footsteps, correspond most accurately. The hind-foot (Pl. 26",) is drawn from one on this slab. Pl. 26′′ is drawn from a plaster

Fishes. The inaccessible recesses of the waters they inhabit, renders the study of their nature and habits much more difficult than that of terrestrial animals. The arrangement of this large and important class of Vertebrata was the last great work undertaken by Cuvier, not long before his lamented death, and nearly eight thousand species of living Fishes had come under his observation. The full developement of their history and numbers, and of the functions they discharge in the economy of nature, he has left to his able successors.

The fact of the formation of so large a portion of the surface of the earth beneath the water, would lead us to expect traces of the former existence of Fishes, wherever we have the remains of aquatic Mollusca, Articulata, and Radiata. Although a few remarkable places have long been celebrated as the repositories of fossil Fishes, even of these there are some, whose geological relations have scarcely yet been ascertained, while the nature of their Fishes remains in still greater obscurity.*

cast in the British Museum, taken from another slab found in the same quarries, and impressed with footsteps of some small aquatic Reptile.

Some fragments of bones were found in the same quarries with these footsteps, but were destroyed.

A thin deposite of Green Marl, which lay upon the inferior bed of sand, at the time when the footsteps were impressed, causes the slabs above and below it to part readily, and exhibit the casts that were formed by the upper sand, in the prints that the animals had made on the lower stratum, through the marl, while soft, and sufficiently tenacious to retain the form of the footsteps.

*The most celebrated deposites of fossil Fishes in Europe are the coal formation of Saarbrück, in Lorraine; the bituminous slate of Mansfeld, in Thuringia; the calcareous lithographic slate of Solenhofen; the compact blue slate of Glaris; the limestone of Monte Bolca, near Verona; the marlstone of Oeningen, in Switzerland; and of Aix, in Provence.

Every attempt that has yet been made at a systematic arrangement of these Fishes has been more or less defective, from an endeavour to arrange them under existing genera and families. The imperfection of his own, and of all preceding classifications of Fishes, is admitted by

The task of arranging all this disorder has at length been undertaken by an individual, to whose hands Cuvier at once consigned the materials he had himself collected for this important work. The able researches of Professor Agassiz have already extended the number of fossil Fishes to two hundred genera, and more than eight hundred and fifty species.* The results of this inquiry throw a new and most important light on the state of the earth, during each of the great periods into which its past history has been divided. The study of fossil Ichthyology is therefore of peculiar importance to the geologist, as it enables him to follow an entire Class of animals, of so high a Division as the vertebrate, through the whole series of geological formations; and to institute comparisons between their various conditions during successive Periods of the earth's formation, such as Cuvier could carry only to a much more limited extent in the classes of Reptiles, Birds, and Mammifers, for want of adequate materials.

The system upon which M. Agassiz has established his classification of recent Fishes is in a peculiar degree applicable to fossil Fishes, being founded on the character of the external coverings, or Scales. This character is so sure and constant, that the preservation even of a single scale, will often announce the genus and even the species of the animal from which it was derived; just as certain feathers announce to a skilful ornithologist the genus or species of a Bird. It follows still farther, that as the nature of their outward covering indicates the relations of all animals to the external world, we derive from their scales certain indications of the

Cuvier; and one great proof of this imperfection is that they have led to no general results, either in Natural History, Physiology, or Geology.

*No existing genus is found among the fossil Fishes of any stratum older than the Chalk formation. In the inferior chalk there is one living genus, Fistularia; in the true chalk, five; and in the tertiary strata of M. Bolca, thirty-nine living genera, and thirty-eight which are extinct.Agassiz.

relations of Fishes ;* the scales forming a kind of external skeleton, analogous to the crustaceous or horny coverings of Insects, to the feathers of Birds, and the fur of Quadrupeds, which shows more directly than the internal bones, their adaptation to the medium in which they lived.

A farther advantage arises from the fact that the enamelled condition of the scales of most Fishes, which existed during the earlier geological epochs, rendered them much less destructible than their internal skeleton; and cases frequently occur where the entire scales and figures of the Fish are perfectly preserved, whilst the bones within these scales have altogether disappeared; the enamel of the scales being less soluble than the more calcareous material of the bone.t

*The foundation of this character is laid upon the dermal covering, the skin being that organ which, more than any other part of the body, shows the relation of every animal to the element in which it moves.

The form and conditions of the feathers and down show the relation of Birds to the air in which they fly, or the water in which they swim or dive. The varied forms of fur and hair and bristles on the skins of Beasts are adapted to their respective place, and climate, and occupations upon the land. The scales of Fishes show a similar adaptation to their varied place and occupations beneath the waters.

Mr. Burchell informs me that he has observed, both in Africa and South America, that in the order of Serpents a peculiar character of the scales appears to indicate a natural subdivision; and that in that tribe, to which the Viper and nearly all the venomous Snakes belong, an acute ridge, or carina, along each dorsal scale may be considered as a distinctive mark.

+ The following are the new Orders, in which M. Agassiz divides the Class of Fishes.

First Order, PLACOIDIANS. (Pl. 27, Figs. 1, 2, Etym. λağ, a broad plate.) Fishes of this Order are characterized by having their skin covered irregularly with plates of enamel, often of considerable dimen. sions, and sometimes reduced to small points, like the shagreen on the skins of many Sharks, and the prickly, tooth-like tubercles on the skin of Rays. It comprehends all the cartilaginous fishes of Cuvier, excepting the Sturgeon,

The enamelled prickly tubercles on the skin of Sharks and Dog-Fishes VOL. I.-18