صور الصفحة
PDF
النشر الإلكتروني

nera.

face of enamel, as in the bony pike and sturgeon. The third order of Ctenoidians have their scales jagged or pectinated like a comb, as in the perch; and his fourth order of Cycloideans has the scales smooth at the margin, and often ornamented with various figures, as in the herring and salmon.

The distinction between the fossil and the recent species, and the formations in which they occur, is one of the most important topics in Geology. Professor Agassiz has extended the number of fossil genera to 200, containing more than 850 species. According to this eminent naluralist, no existing genus occurs among the fossil fishes in any stratum older than the chalk formation. In the inferior chalk there is only one living 'genus,--the Fistularia; in the true chalk five, while in the tertiary strata of Monte Bolca there are thirty-nine existing, and thirty-eight extinct ge

The two orders of Placoideansand Ganoideans oply existed before the commencement of the chalk formations. The Ctenoideans and Cycloideans, which contain three-fourths of the eight thousand known species of existing fishes, appear in the chalk strata for the first time, when all the fossil genera of the two first orders had become extinct.

The great importance ofthe character, derived from the scales, may be deduced from the fact, that the enamelled state of the scales of those fishes, which existed in the earlier epochs, rendered them more enduring than the bones; and the character is besides so invariable, that a single scale is often sufficient to determine the animal to which it belonged.

The fossil remains of the mollusca, whether of the naked genera or of those protected by a shell, furnish Dr Buckland with new proofs of Divine wisdom. Among these bodies we have carnivorous and herbivorous races; the former being provided with a proboscis armed with teeth like those of a rasp, for perforating the shells of their prey, and extracting through the aperture the juices which are to feed them; while the latter have jaws formed for feeding upon vegetables. The naked mollusca, however, exhibit the most interesting phenomena. The euttle-fish, it is well known, protects itself from its enemies, by ejecting from a bladder-shaped sac, a black and viscid ink which hides it in the surrounding opacity which it creates. This ink-bag, distended as during the life of the animal, has been found in a fossil state by Miss Mary Anning, in the lias of Lyme Regis; the ink itself being preserved in a dried state, with its original bulk not greatly diminished, and possessing all its properties of a pigment. Besides the ink-bag, there was found also a horny pen, like the pen of a recent loligo, and retaining traces even of its minutest libres of growth.

Dr. Buckland proceeds at great length to discuss the natural theology of fossil shells; and illustrates his descriptions and his arguments with numerous and splendid engravings. But our waning limits remind us, that whilst we are discussing the length of time, we are encroaching on the shortness of our space; and we must therefore pass, with an accelerated velocity, over the remainder of the work, -substituting our meagre abstract in place of the copious and fervid eloquence of the author. In the chambered shells of the naytili and the ammonites there are many beautiful adaptations. They are provided with elegant hydraulic apparatuses for enabling them to advance beneath the water, and at other times to rise and float upon its surface. The chambers of the nautilus perform the functions of air-vessels, or floats, by which it can rise or sink by vårying its specific gravity; and while it floats with its expanded arms, it moves in a retrograde direction by the reaction of the water which it ejects from a funnel. In the construction of the kindred ammonites are found the same beautiful mechanism. Its delicate shell resists the external pressure of the sea by transverse stays and bracings, which combine lightness with strength; and the edges of their supports adorn the exterior shell with a succession of graceful forms like the most elegant embroidery.

In the fossil Belemnites we find the same phenomenon of an ink-bag which the cuttle-fish enjoys, and soine of these bags are nearly a foot in length.

The Nammulites, the greater number of which are microscopic, surnish our author with the materials of an interesting section. Their shells, which resemble a piece of money, have their aić chambers like the nautilus; and at an early epoch, they must have floated in countless swarms upon the sea. In the later members of the secondary, and in many of the tertiary strata, they are piled on each other like grains of corn in a heap; they abound in the limestone which composes some of the Pyramids and the Sphinx; and they often form much of the entire bulk of many extensive mountains.

The Trilobites are objects of still higher interest. They are distributed most extensively over the globe, and form an entirely extinct race of crustaceous animals, equally remarkable for their antiquity, and their strange peculiarities of configuration. Not a single trilobite has been found in any strata newer than the carboniferous series. The structure of their eyes, which have been

[ocr errors]

* Dr Leach's genus serolis is the only recent one which approaches to the trilobites.

6

6

preserved during incalculable ages in the early strata of the transition formation, calls forth the eloquence and ingenuity of our author. We have, in a previous article, given a brief notice of the eyes of insects and crustacea;* and shall, therefore, confine ourselves to the results deduced by Dr Buckland. The existence of such eyes among the most ancient forms of animal life, and their occurrence in the limulu during the middle periods of geological chronology, when the secondary strata were deposited, give us positive information, not only respecting the condition of the sea and the atmosphere of these olden times, but also of the relation of these two media to light. The waters which admitted light to the eye of the trilobite . could not have been the imaginary

turbid and chaoty fluid' of the Neptunian geologists; and the atmosphere which conveyed that light to the deep, could not have differed materially from its present condition. The mutual re• lations, 100, of light to the eye, and of the eye to light, were

the same at the time when crustaceans, endowed with the faculty of vision, were first placed at the bottom of the primeval seas, as at the present moment.'

The sections on fossil spiders, scorpions, insects, and the chapter on fossil radiated animals, or zoophytes, including the encrinites and the pentacrinites, are full of interest. The vast beds of entrochal marble that extend over Europe and America are often as entirely composed of the petrified bones of encrinites, “as a • corn-rick is composed of straws.'— Man,' as our author elo

quently remarks, * employs it to construct his palace and adorn • his sepulchre; but there are few who know and fewer still who * duly appreciate the surprising fact, that much of this marble is

composed of the skeletons of millions of organized beings, once • endowed with life and susceptible of enjoyment.”

The Briarean pentacrinite, so called, from the number of its side arms, is remarkable for the number of bones in its fingers, and tentaculæ, and side arms. Dr Buckland computes them at a hundred and fifty thousand; and to these he adds three hundred thousand fasciculi of fibres, equivalent to muscles in the body of a single pentacrinite.

The proofs of design in the structure of fossil plants, furnish our author with the materials of an instructive chapter. The number and species of living plants amounts at present to about 50,000 species. The fossil plants yet described do not exceed 500. Nearly 300 of these are obtained from the transition series, and almost wholly from the coal formation. Another hundred have been found in the strata of the secondary series, and upwards of a hundred from formations of the tertiary series.

* See this Journal, No. 121, p. 178.

The plants of the first period consist chiefly of ferns and gigantic equisetacæ; and of families intermediate between existing lycopodeace and coniferæ, and a few coniferæ.

Those of the second period consist of ferns, cycladæ and coniferæ with a few liliaceæ; the ferns being one-third of the whole.

The plants of the third period approach closely to our existing species.

Sea weeds occur in the strata coeval with the most ancient animals; and their continuance throughout all subsequent formations, of a marine origin, has been established by M. A. Brongniart.

The indications of climate which may be drawn from plants and animals, especially those which are terrestrial, may in a future state of our knowledge throw much light upon the early meteorology of our planet.

lọ this chapter Dr Buckland has given a very interesting account of the plants to which we may trace the origin of coal. He describes the fossil plants in the Newcastle coal pits; but in the coal mines of Bohemia he observed the finest examples of distinctly preserved vegetable remains. The most elaborate • imitations of living foliage upon the painted ceilings of Italian

palaces bear no comparison with the beauteous profusion of ex• tinct vegetable forms by which the galleries are overhung. • The roof is covered with a canopy of gorgeous tapestry, enriched

with festoons of most graceful foliage, flung in wild irregular • profusion over every portion of its surface.'

• The spectator feels himself transported, as if by enchantment, into . the forests of another world. He beholds trees, of forms and • characters now unknown upon the surface of the earth, pre* sented to his senses almost in the beauty and vigour of their · primeval life-their scaly stems and bending branches, with • their delicate 'apparatus of foliage, are all spread forth before • bim, little impaired by the lapse of countless ages, and bearing faithful records of extinct systems of vegetation which began

and terminated in times of which these relics are the infallible • historians.'

Dr Buckland's work is terminated with six short, but interesting chapters of a general but very interesting nature.' He considers the proofs of desigo which are exhibited in the disposition of the strata of the coal formation,-in the disturbing forces which have given origin to mineral veins, and placed the useful metals in the most advantageous positions,--and in the physical forces of a more particular nature, by which strata have been sunk or ele

6

6

vated, inclined, and twisted, and broken, and dislocated, to produce all that variety of character and of form which marks the surface of the globe. He treats of the adaptation of the earth to afford supplies of water through the medium of springs; and he gives us much curious information on the subject of Artesian wells. His last chapter explains the proofs of design in the structure and composition of unorganized mineral bodies; and he concludes with an eloquent and glowing peroration on the unity of the Deity; the proofs of successive creations; the connexion of religion and science; and the end of all secular knowledge— to ' penetrate our understanding with profound and sensible per* ceptions of the “high veneration man's intellect owes to • God.”?

Such is a brief, we sear, indeed, a too condensed, analysis of Dr Buckland's work,-a work as much distinguished for the industry and research which it indicates, as for its scientific principles and philosophical views. The extraordinary and inestimable facts which he has brought under the grasp of the general reader, have been illustrated by numerous and splendid embellishments; and while his descriptions of them are clothed in simple and perspicuous language, the general views to which they lead have been presented to us in the highest tone of a lofty and impressive eloquence. We have ourselves never perused a work more truly fascinating, or more deeply calculated to leave abiding impressivps on the heart; and if this shall be the general opinion, we are sure that it will be the source of higher gratification to the author than the more desired, though on his part equally deserved, meed of literary renown.

In the course of our analysis we have been occasionally perplexed to discover the cause of that exciting interest which this volume awakens even in minds familiar with the grander phenomena of nalure. That the wonders of fossil geology are the latest acquisitions of Natural Theology is certainly not the reason why they appear to be the most interesting. In the living mechaņisms around us, and in the most familiar functions of animal physiology, we have superabundant proofs of matchless skill and benevolent adaptation, but the mind of man, prejudiced even in its piety, does not appreciate as it ought, these miracles of power. There is something unclean about animal bodies, and iheir functions, and their products, which deters all but professional men from their study, and therefore robs them of their inherent claims as incentives to piety and as proofs of design. But the case is wholly altered when we are introduced to fossil skeletons; and examine the structure and functions of animals that inhabited the earth long before its occupation by man.

« السابقةمتابعة »