Chapter VIII: Part II: Fossil Fauna (4)

A general idea of the nature of the compound coral-zoophytes may be obtained by the examination of the common _Flustra_ or Sea-mat. This form of polyparia, when taken out of the water, appears to the naked eye like a patch of fine varnished net-work, adhering to a piece of sea-weed or stone; when viewed with a magnifying lens of moderate power, the surface is found beset with pores regularly disposed: and if the Flustra be examined while immersed in sea-water, its surface is seen to be invested by a gelatinous substance, and every pore is the aperture of a cell, whence issues a tube fringed at the extremity with long tentacula or feelers. These expand, then suddenly contract, withdraw into the cell, and again issue forth: the whole surface of the Flustra being studded with the hydra-like animalcules; each enjoying a distinct existence, the entire group being united by one common integument or calcareous frame-work. When the Flustra is exposed to the air, the polypes soon perish, the animal matter rapidly decomposes, and the calcareous lace-like skeleton alone remains. In the larger and more compact corals the phenomena are similar, differing only in degree. In a fossil state, the durable remains of the corals consist for the most part of the calcareous frame-work (or polyparium, as it is termed), which often possesses a crystalline structure; and in some instances is completely transmuted into silex, as in specimens from Antigua, the Falls of the Ohio, and from Tisbury in Wiltshire. (See Plate XXXVIII. figs. 12, 13.)

I must refer to the Wonders of Geology for a more extended notice of fossil corals, and other zoophytes, and will only add that the calcareous and siliceous spines or spicula, not only of sponges, but also of Gorgoniæ, and other corals, are often met with in a fossil state.[106]

[Footnote 106: See Wonders of Geology, vol. ii. Lect. vi. p. 634.]

IX. Cuvier's Discoveries. _The Fossil Quadrupeds of Montmartre._ (Plate LXXII.)--The Palæotheria, Anoplotheria, and other genera of extinct quadrupeds related to the _Tapir_, whose remains were first noticed in the gypseous limestone of Montmartre, near Paris, and which have since been found in many other localities of the same strata, are familiar to every one, from the just celebrity attached to the labours of the illustrious Cuvier, who restored as it were these lost denizens of an earlier world, in their native character and forms, and distinguished them by names long since become classical in the sciences which treat of the ancient history of the earth and its inhabitants.

The gypsum quarries spread over the flanks of Montmartre were many years since known to contain fossil bones of extinct quadrupeds, and some of these had been figured and described in 1768 by Guettard, and afterwards by Pralon, Lamanon, and Parumot: but it was not till the attention of M. Cuvier was directed to the subject by some specimens put into his hands by M. Vuarin, that the interest and importance of these fossils were understood. The curiosity of Baron Cuvier was so much excited by an inspection of a large collection of these bones, soon after he had been successfully engaged in the investigation of the remains of fossil Elephants and Mastodons, that he immediately began to obtain specimens from the quarries, and by liberally rewarding the workmen, and by unremitting personal research, he soon accumulated an immense quantity of bones of all sorts, belonging to numerous individuals. He now perceived that a new world was open to his view: and to use his own expressive language, he found himself in an ancient charnel-house, surrounded by a confused multitude of mangled skeletons of a great variety of unknown beings. To arrange each fragment in its proper place, and restore order to these heterogeneous materials, seemed at first a hopeless task: but a knowledge of the immutable laws by which the organization of animal existence is governed, soon enabled him to assign to each bone, and even fragment, its proper place in the skeleton; and the forms of beings hitherto unseen by mortal eye appeared before him. "I cannot," he exclaims, "express my delight in finding how the application of one principle was instantly followed by the most triumphant results. The essential character of a tooth and its relation to the skull being determined, all the other elements of the fabric immediately fell into their proper places; and the vertebra, ribs, bones of the legs, thigh, and feet, seemed to arrange themselves even without my bidding, and in the very manner I had predicted." The principles of the correlation of structure which his profound researches in comparative anatomy had enabled him to establish, conducted to these important results, and laid the foundation of that science which has since received the name of Palæontology.[107] The mode of induction adopted by this illustrious philosopher, has been the mighty instrument by which subsequent labourers in this department of science have so largely contributed to our knowledge of the ancient condition of the earth, and of the structure and economy of the tribes of beings which have successively dwelt upon it. The examination of the fossil teeth (in Plate LXXII. figs. 4-9) showed that the animals were herbivorous; and the crown of the tooth being composed of two or three simple crescents, as in certain pachydermata, proved that they differed from the ruminants, which have double crescents, and each four bands of enamel. The two principal genera first established were the _Palæotherium_ and _Anoplotherium_. The first approximates to the Tapirs in the number and disposition of the teeth; the second is remarkable in having no projecting canines, and in all the teeth forming a continued series, as in the human race. Remains of both these genera have been found in the eocene tertiary strata of the Isle of Wight,[108] and on the coast of Hampshire.

[Footnote 107: A concise exposition of the Cuvierian inductive philosophy will be found in Wonders of Geology, pp. 137-147.]

[Footnote 108: See my Geological Excursions round the Isle of Wight. For an account of the fossil animals of Paris, refer to Wonders of Geology, p. 254.]

X. Fossil Edentata. _Megatherium, and Megalonyx_. (Plates LXXII. and LXXIII.)--The remains of these and other allied forms of the extinct gigantic Edentata, which once inhabited South America, occur in immense quantities throughout the Pampas--those vast plains which present a sea of waving grass for 900 miles. These plains consist of alluvial loam and sand, containing fresh-water and marine shells of existing species; they were evidently once, like Lewes Levels, a gulf or arm of the sea. Since the publication of Mr. Parkinson's work, vast numbers of bones have been exhumed, and many most interesting specimens sent to England by Sir Woodbine Parish, and Charles Darwin, Esq., in whose charming "Journal of Researches into the Natural History and Geology of the Countries visited during the Voyage of H.M.S. Beagle round the World," will be found many highly graphic notices of the discovery of these remains.[109] Mr. Darwin, under the head of _Bahia Blanca_,[110] describes the remains of no less than nine great quadrupeds found imbedded within the space of 200 square yards. They consisted of three heads and other bones of the _Megatherium_, of enormous dimensions; and bones of the _Megalonyx_. Of the _Scelidotherium_, an allied animal, Mr. Darwin obtained an almost perfect skeleton; it must have been as large as a rhinoceros; in the structure of the head, it approaches nearest the Cape ant-eater, in other respects it is related to the armadilloes. Remains of a different species of Mylodon, of another gigantic edental quadruped, and of a large animal with an osseous dermal coat in compartments, very like that of the Armadillo. Of this last, which has been named _Glyptodon_, there is a very fine specimen in the Hunterian Museum. Teeth and bones of an extinct species of horse, and of an unknown pachyderm, a huge beast with a long neck like the camel. Lastly the _Toxodon_ (so named from the remarkable curvature of the teeth); this is perhaps one of the strangest animals ever discovered. In size it equals the elephant or megatherium, but the structure of its teeth shows it to have been intimately related to the gnawers--the order which at the present day includes the smallest quadrupeds. In many details it approaches to the pachydermata; judging from the position of its eyes, it was probably aquatic, like the Dugong and Manatee, to which it is also allied.

[Footnote 109: Published by Mr. Murray, in one vol. 1845. The anatomical description of the fossil Edentata brought home by Mr. Darwin, by Professor Owen, will be found in the "Zoology of the Voyage of the Beagle."]

[Footnote 110: Mr. Darwin's Journal, chap. v. p. 81.]

The beds containing the above fossil remains, consist of stratified gravel and reddish mud, and stand only from fifteen to twenty feet above the level of high water; hence the elevation of the land has been small since the great quadrupeds wandered over the surrounding plains; and the external features of the country must then have been very nearly the same as now.

In another place, Mr. Darwin observes,--"The number of the remains of these large quadrupeds imbedded in the grand estuary deposit which forms the Pampas and covers the granitic rocks of Banda Oriental, must be extraordinarily great. I believe, a straight line drawn in any direction through the Pampas, would cut through some skeleton or bones. Besides those which I found during my short excursions, I heard of many others; and the origin of such names as, 'the stream of the animal,' 'the hill of the giant,' is obvious. At other times, I heard of the marvellous property of certain rivers, which had the power of changing small bones into large; or as some maintained, the bones themselves grew. As far as I am aware, not one of these animals perished, as was formerly supposed, in the marshes or muddy river-beds of the present land, but their bones have been exposed by the streams intersecting the subaqueous deposit, in which they were originally imbedded. We may conclude that the whole area of the Pampas is one wide sepulchre of these extinct gigantic quadrupeds."[111]

[Footnote 111: Mr. Darwin's Journal, p. 135. The reader interested in these extraordinary fossil remains should visit the British Museum, and the Hunterian Museum of the Royal College of Surgeons in Lincoln's Inn Fields.]

XI. Flint.--_Animal Remains in siliceous nodules._--So many beautiful specimens of siliceous petrifactions--that is, animal and vegetable remains transmuted into silex or flint--are figured in the subjoined plates, that it may be useful to offer a few remarks on this subject.[112] In many instances the organic remains in chalk-flints are simply incrusted by the silex; such is the state of numerous sponges which are as it were invested by the flint, and have all their pores and tubes filled up by the same material, the original tissue appearing as a brown calcareous substance. In other examples, the sponge has been enveloped in a mass of liquid flint, and has subsequently perished and decomposed; in this manner have been formed those hollow nodules, which on being broken present a cavity containing only a little white powder, or some fragments of silicified sponge; in many instances the cavity is lined with quartz crystals, or mammillated chalcedony. Frequently but part of the zoophyte is permeated by the silex, and the other portion is in the state of a friable calcareous earth imbedded in the chalk. Sponges and other zoophytes often form the nuclei of the flint nodules; the original substance of the organic body being in general silicified, and the most delicate internal structure preserved. Shells, corals, and the minute cases of foraminifera, are often immersed as it were in pure flint, appearing as if preserved in a semi-transparent medium.

[Footnote 112: See Wonders of Geology, vol. i. pp. 74-105, for a general view of the process of petrifaction.]

But there are innumerable flint nodules in which no traces of spongeous tissue are apparent, and veins, dikes, and sheets of tabular flint, that are in a great measure free from organic remains; containing only such as may be supposed to have become imbedded in a stream of fluid silex that flowed over a sea-bottom. Wood perforated by lithodomi and silicified, is occasionally met with; and fuci or algæ are sometimes found, appearing as if floating in the liquid flint.

For the most part, the minute shells in the chalk and flint are filled with amorphous mineral matter; but in many examples, (as I have ascertained by direct experiment,) the soft parts of foraminifera remain in the shell.

XII. Foraminifera.--Plate LXII. contains figures of several species belonging to various genera of those minute fossil shells, the discoidal involute forms of which were once considered to belong to the Cephalopoda, and to be related to the Nautilus, Spirula, &c., but which are now grouped in one family, under the name of _Foraminifera_; a term derived from the foramina or perforations with which their shells are traversed, and which have relation to the peculiar organization of the animals.

Since microscopic observations have become so general, thanks to the genius and enthusiasm of Ehrenberg, these fossil bodies have acquired a degree of interest and importance, unsurpassed by more obvious organic remains. Whole mountain chains and extensive tracts of country are now known to be almost entirely composed of the aggregated shells of a few genera of these _microzoa_.[113] In other deposits their remains are associated with those of _Infusoria_,[114] (both animal and vegetable,) still more infinitesimal. As much error prevails among collectors as to the real nature of the fossil foraminifera, I am induced to annex the following remarks.[115]

[Footnote 113: A convenient term to express animal organisms that can only be distinctly examined by the aid of the microscope: strata in a great measure composed of such fossil remains may be distinguished as _microzoic_ deposits.]

[Footnote 114: This term was first employed to denote the various minute forms of animal organization that appear in vegetable infusions; as Rotifers, Monads, Vorticella, &c. But with these, numerous vegetable forms generally appear, as Gaillonella, Bacellaria, Navicula, &c.: these were formerly also regarded as animals, and were consequently comprised under the same general appellation.]

[Footnote 115: The best scientific account of these animals will be found in M. D'Orbigny's work on the "Foraminifères Fossiles du Bassin Tertiaire de Vienne, (Autriche)." Paris, 1846. 1 vol. 4to, with plates.]

The foraminifera are marine animals of low organization, and, with but few exceptions, extremely minute: in an ounce of sea-sand between three and four millions have been distinctly enumerated. When living, they are not aggregated, but always individually distinct; they are composed of a body (or vital mass) of a gelatinous consistence, which is either entire, and round, or divided into segments, placed either on a simple or alternate line, or coiled spirally, or involuted round an axis. This body is covered with an envelope or shell, which is generally testaceous, rarely cartilaginous, and is modelled on the segments, and follows all the modifications of form and contour of the body. From the extremity of the last segment, there issue, sometimes from one, sometimes from several openings of the shell, or through numerous pores or foramina, very elongated, slender, contractile, colourless filaments, more or less divided and ramified, serving for prehension, and capable of entirely investing the shell. The body varies in colour, but is always identical in individuals of the same species,--it is yellow, fawn-coloured, red, violet, blue, &c. Its consistence is variable; it is composed of minute globules, the aggregation of which determines the general tint. It is sometimes entire, round, and without segments, as in _Gromia_, _Orbulina_, &c., which represent, at all ages, the embryonic state of all the other genera. They increase, without doubt, by the entire circumference. When the body is divided by lobes or segments, the primary lobe, as in the permanent condition of the Gromia, is at first round or oval, according to the genus; once formed it never enlarges, but is enveloped externally by testaceous matter; it may be compared to a ball on which is applied a second larger one, then a third still larger, and so on during the life of the animal.

The annexed figure of the animal of _Nummulina_ (as given by MM. Joly and Leymerie) will serve to convey a general idea of the living Foraminifera.

The segments, as the body increases, are agglomerated in six different ways, and these modifications are the basis of M. D'Orbigny's classification. The discoidal forms, as the _Rotalia_, _Rosalina_, _Cristellaria_, &c. are involuted like the nautilus, and divided by septa or partitions, the different lobes of the body occupying contemporaneously every chamber, and being connected by a tube or canal that extends through the entire series. In the spiral forms, the _Textilaria_, &c. the same structure is apparent. These two groups are the most abundant in the cretaceous strata; many beds of the white chalk consist almost wholly of the aggregated shells of the Rosalinæ, Rotaliæ, and Textilariæ.[116] Whatever the form of the body, the filaments always consist of a colourless matter as transparent as glass; they elongate from the base to six times the diameter of the shell. They often divide and subdivide, so as to appear branched. Though alike in form in the different genera, they vary much in their position. In some they form a bundle which issues from a single opening, and is withdrawn into the same by contraction; in others the filaments project only through each of the pores in the shell which covers the last segment; in others they issue from both the large aperture and the foramina. In fine, these filaments or pseudopodia fulfil in the foraminifera the functions of the numerous tentacula in the Asteriadæ, or Star-fishes, serving as instruments of locomotion and attachment.

[Footnote 116: See Wonders of Geology, p. 299]

Neither organs of nutriment nor of reproduction have been detected. In the genera having one large aperture from which the filaments issue and retract, we can conceive nutriment to be absorbed by that opening; but this cannot be the case in the species which have the last cell closed up; in these the filaments issuing through the foramina are probably also organs of nutrition. M. D'Orbigny considers the Foraminifera as constituting a distinct class in zoology; less complicated than the Echinoderms and the Polypiaria in their internal organization, they have by their filaments the mode of locomotion of the first, and by their free, individual existence--not aggregated and immovably fixed--they are more advanced in the scale of being than the latter. To me they appear to be merely hydra-form polypes of the most simple structure, protected by shells;[117] those composed of different segments, I conceive to be a single aggregated individual, and not a successive series of beings.

[Footnote 117: An admirable paper on the "_Polystomella crispa_," by Mr. Williamson, of Manchester, (Trans. Micros. Society of London, vol. ii.) should be consulted on this question.]

The white chalk is well known to be largely composed of a few kinds of foraminifera, but the occurrence of the soft bodies of these animalcules in a fossil state was first discovered by me, in 1845, in chalk-flints, and was announced in a paper, read before the Geological Society, entitled, "_Notes of a Microscopical Examination of Chalk and Flint_."[118] This statement was regarded by some eminent palæontologists as so "startling and unsatisfactory," that I resumed the investigation, and communicated the result to the Royal Society, in a memoir "_On the Fossil Remains of the Soft Parts of Foraminifera discovered in the Chalk and Flint of the South-East of England_;"[119] and with the kind assistance of that able chemist and microscopist, Mr. Henry Deane, of Clapham Common, I obtained, by immersing chalk in dilute hydrochloric acid, and mounting the residue in Canada balsam, several specimens of the entire integuments of the bodies of Rotaliæ, as distinct as if recent! This fact is now admitted; and the experiment has been successfully repeated in India, by Mr. Carter, on the limestones of that country;[120] and in America, by Dr. Bailey, &c.[121] In some limestone recently collected by my eldest son, Mr. Walter Mantell, in the Middle Island of New Zealand, and which, like our cretaceous strata, is almost entirely made up of foraminifera, I have detected the soft parts of the bodies of Rotaliæ in the cells of the fossil shells, as distinctly as in the chalk of England; and two of the species appear to be identical with European forms.

[Footnote 118: These "Notes" were withdrawn, and published in the Annals of Natural History for August, 1845.]

[Footnote 119: Published in Philos. Trans. Part iv. for 1846.]

[Footnote 120: "On the existence of Beds of Foraminifera, recent and fossil, on the South-East of Arabia," by H. J. Carter, Esq. Assistant Surgeon, Bombay. Proceedings of the Bombay Asiatic Society, 1848.]

[Footnote 121: A remarkable foraminiferous deposit of chalk detritus occurs at Charing, in Kent, and was first examined and described by William Harris, Esq.; it contains immense numbers of many kinds of foraminifera, and of the cases or shells of entomostraca, of the genus Cytherina, with spicules of sponges, &c.--See Wonders of Geology, vol. 1. p. 324.]

M. D'Orbigny gives the following summary of the distribution of the known fossil species of Foraminifera:--

There are 228 species in the Tertiary deposits of Vienna alone, of which twenty-seven species are known living in the Adriatic and the Mediterranean.

Foraminifera are unknown in the Silurian and Devonian formations.

One species only is known in the Carboniferous system of Russia, the _Fusulina cylindrica_.

Jurassic or Oolitic formation Genera 5 Species 20
Cretaceous " 34 " 280
Tertiary " 56 " 450
Living in the present seas " 68 " 1,000

Of these last, 575 species inhabit tropical seas, 350 the seas of temperate, and 75 the seas of cold climates.

XIII. Fossil Elk of Ireland, or _Cervus megaloceros_. (Plate LXXI.)--The shell-marls of Ireland contain in abundance the bones of an animal, which like the Dodo, was once contemporary with the human species, but has long been extinct: the last individuals of the race were, in all probability, exterminated by the early Celtic tribes. The remains of this noble creature generally occur in the deposits of marl that underlie the peat-bogs, which are apparently, like those of Scotland, the sites of ancient lakes or bays. In Curragh immense quantities of these bones lie within a small area; the skeletons appear to be entire, and are found with the skull elevated, and the antlers thrown back on the shoulders, as if a small herd of these Elks had sought refuge in the marshes, and had been engulfed in the morass, in the same manner as the Mastodons of America. (See description of Plate LXXIV., ante, p. 167.)

This creature far exceeded in magnitude any living species of elk or deer. The skeleton is upwards often feet in height to the top of the skull, and the antlers are from ten to fourteen feet from one extremity to the other. The fine perfect skeletons in the British Museum, College of Surgeons, and in the Museum at Edinburgh, render a particular description unnecessary. The bones are generally well preserved, of a dark brown colour, with patches of blue phosphate of iron. In some instances they are in so fresh a condition, that the hollows of the long bones contain marrow having the appearance of fresh suet. Remains of this majestic animal have been found collocated with ancient sepulchral urns, stone implements, and rude canoes, in such manner, as to leave no doubt that this now extinct deer was coeval with the early human inhabitants of these Islands. Its bones and antlers have been found at Walton, in Essex, associated with the remains of the Mammoth, or fossil elephant.[122]

[Footnote 122: Wonders of Geology, p. 134.]

XIV. Fossil Infusoria--_Infusorial Earths_.--In the note on Foraminifera some account is given of various rocks composed of the fossil remains of those minute animals; but the durable relics of the yet more infinitesimal organisms designated by the terms _Infusoria_, or _Infusorial animalcules_, form deposits of equal interest and importance. Strata of great extent and thickness are wholly, or in great part, made up of innumerable layers, consisting of the aggregated siliceous cases or shields of Infusoria: and similar structures are found to be the chief constituents of the white earthy deposits of lakes, rivers, and basins of brackish water, in every part of the world.

Slowly, imperceptibly, but incessantly, are the vital energies of the feeblest and minutest animal and vegetable existences separating from the element in which they live, the most enduring of mineral substances, silex--fabricating it into structures of the most exquisite forms and sculpturing, and thus adding to the accumulations of countless ages, which make up the sedimentary strata of the crust of the globe.

In the "Medals of Creation"[123] will be found a summary of what was then known as to the formation and composition of many tertiary deposits which the indefatigable Ehrenberg, Dr. Bailey, and other eminent observers, had carefully investigated and described. The five years that have since elapsed have been fruitful in results of the most important and interesting character; from every quarter of the world, from the loftiest mountain peaks, and from the deepest recesses of the ocean which the plummet can reach, from the ashes of volcanoes and from the snow of the glaciers, the durable remains of Infusoria have been obtained. That excellent scientific periodical, Silliman's American Journal, contains numerous interesting communications on this subject from the eminent chemical professor of the Military College at West Point, Dr. J. W. Bailey; and the labours of Mr. Bowerbank, Williamson, and other active members of the Microscopical Society of London, have yielded much interesting information on the infusorial deposits of our own country.

[Footnote 123: Medals of Creation, vol. i. p. 211.]

The present note will be restricted to remarks on the nature of the organisms which enter so largely into the composition of certain tertiary deposits; since the opinion once entertained of the animal nature of many infusoria, now regarded as true vegetables, materially affects the geological conclusions respecting the persistence of certain species of organisms through long periods of time, during which the mollusca, zoophytes, &c. underwent repeated mutations both in the species and genera. Thus, for example, the _polierschiefer_, or polishing-slate of Bilin, and the berghmehl of Tuscany, are described by Ehrenberg as masses of the siliceous shells of animalcules of such extreme minuteness, that a cubic inch of the stone contains upwards of forty millions; the infusorial earth of Richmond, in Virginia, in like manner, is stated to be made up of the siliceous skeletons of animalcules of infinitesimal minuteness. But later investigations have (I conceive) satisfactorily established, that the greater part of these fossil organisms belongs to the vegetable and not to the animal kingdom.[124] The whole of the figures in Plate IV. of the "Medals of Creation," described as living Infusoria, on the authority of Ehrenberg, are undoubted vegetables, belonging to the great botanical groups called _Diatomaceæ_ (from the angular segments into which they separate by partial division), and _Desmidiaceæ_.[125] The entire family of _Bacillaria_ belongs to this group. These simplest forms of vegetable structures abound in every lake or stream of fresh and brackish water, in every pool, or bay, and throughout the ocean, from the equator to the poles; they secrete siliceous envelopes, which present an endless variety of form and structure, and after the death and decomposition of the perishable tissues of the plants, remain as perfectly transparent colourless shields of pure silica; such are the _Gaillonellæ_, _Euastra_, _Closteria_, _Naviculæ_, _Synhedræ_, _Podospheniæ_, _Xanthidia_, &c., which constitute so large a proportion of the infusorial earths described by Ehrenberg and other authors.[126]

[Footnote 124: In my little work on Recent Infusoria, entitled "Thoughts on Animalcules, or a Glimpse of the Invisible World revealed by the Microscope," I have expressed my conviction of the vegetable nature of these organisms, as a reason for omitting figures and descriptions of any of the species in a work on living fresh-water animalcules.]

[Footnote 125: The name Diatomaceæ is restricted by M. Brébisson to those species which have a siliceous envelope, or cuticle; and that of _Desmidiæ_ to those which are not siliceous, but reducible by heat to carbon.]

[Footnote 126: The reader interested in this subject should consult the beautiful work of Mr. Hassall on the Desmidiaceæ, published by Messrs. Reeve & Benham.]

The extent of this infinitesimal flora throughout regions where no other forms of vegetation are known, is strikingly demonstrated by the observations of the eminent botanist and traveller. Dr. Hooker, in his account of the Antarctic regions.

"Everywhere," he states, "the waters and the ice alike abound in these microscopic vegetables. Though too small to be visible to the unassisted eye, their aggregated masses stained the iceberg and pack-ice wherever they were washed by the sea, and imparted a pale ochreous colour to the ice. From the south of the belt of ice which encircles the globe, to the highest latitudes reached by man, this vegetation is everywhere conspicuous, from the contrast between its colour and that of the white snow and ice in which it is imbedded. In the eightieth degree of south latitude all the surface ice carried along by currents, and the sides of every berg, and the base of the great Victoria barrier itself--a perpendicular wall of ice, from one to two hundred feet above the sea-level--were tinged brown from this cause, as if the waters were charged with oxide of iron. The majority of these plants consist of simple vegetable cells, enclosed in indestructible silex (as other _Algæ_ are in carbonate of lime); and it is obvious that the death of such multitudes must form sedimentary deposits of immense extent.

"The universal existence of such an invisible vegetation as that of the Antarctic ocean, is u truly wonderful fact, and the more so, from its being unaccompanied by plants of a high order. This ocean swarms with mollusca, and entomostracous crustaceans, small whales, and porpoises; and the sea with penguins and seals, and the air with birds: the animal kingdom is everywhere present, the larger creatures preying on the smaller, and these again on those more minute; all living nature seems to be carnivorous. This microscopic vegetation is the sole nutrition of the herbivorous animals; and it may likewise serve to purify the atmosphere, and thus execute in the antarctic latitudes the office of the trees and grasses of the temperate regions, and the broad foliage of the palms of the tropics."[127]

[Footnote 127: From Dr. Hooker's account of the botany of the South Polar regions in Sir J. Ross's Voyages of Discovery.]

Dr. Hooker also observes, that the siliceous cases of the same kind of Diatomaceæ now living in the waters of the South Polar Ocean, have contributed in past ages to the formation of European strata; for the tripoli and the phonolite stones of the Rhine contain the siliceous shields of identical species. Such are the comments of one of our most eminent botanists on the phenomena under review. The reader will probably ask,--What, then, are the essential characters which separate the animal from the vegetable kingdom? To this question it is impossible to give a satisfactory reply: perhaps the only distinction that will be generally admitted by zoologists and botanists is the following:--_animals require organic substances for their support; vegetables derive their sustenance from inorganic matter_.

The facts thus cursorily reviewed throw much doubt on many of M. Ehrenberg's statements as to the identity of species of animalcules now living, with those whose remains occur in the eocene, and in the secondary strata. The so-called _Xanthidia_ of the chalk, are certainly altogether distinct from the recent diatomæ to which the name was first applied; the chalk organisms are probably the gemmules of sponges or other zoophytes.[128]

[Footnote 128: It would be convenient to distinguish these fossils by another name, and thus avoid the perpetuation of the error; I would propose that of _Spiniferites_, in allusion to the numerous spines with which all the species are beset.]

Infusorial earths may therefore be composed either of microscopic vegetable or animal remains, or of both. The brackish and fresh-water deposits I have examined are siliceous and almost wholly diatomaceous: the marine calcareous strata composed of microscopic organisms, consist chiefly of various kinds of foraminifera, a large proportion belonging to the polythalamia, or chambered shells. I am not certain as to the animal or vegetable nature of some of the beautiful siliceous disks (_Coscinodisci_, _Arachnoidisci_, _Actinocyclus_, &c.) so abundant in the Richmond, Barbadoes, and Bermuda infusorial earths, and which occur in so splendid a state in the Guano deposits of Ichaboe.

With the corrections which the above remarks will enable the reader to make, I would refer to the account of Fossil Infusoria in the Medals of Creation, and Wonders of Geology. [129]

[Footnote 129: See also "Thoughts on Animalcules."]

XV. The Mosasaurus, or _Fossil Reptile of Maestricht_. (Plate LXX.) The occasional discovery of bones and teeth of an unknown animal in the limestone of St. Peter's Mountain, near Maestricht, and the innumerable shells, corals, teeth of fishes, claws of crabs, echini, and other organic remains, had long since attracted the attention of naturalists, and rendered these quarries celebrated throughout Europe. In 1770, M. Hoffman, the surgeon of the Fort, who had for some years been assiduously collecting the fossils of this locality, had the good fortune to discover a specimen which has conferred an enduring celebrity on his name. Some workmen, on blasting the rock in one of the caverns of the interior of the mountain, perceived to their astonishment the jaws of a large animal attached to the roof of the chasm. The discovery was immediately made known to M. Hoffman, who repaired to the spot, and for weeks presided over the arduous task of separating the mass of stone containing these remains from the surrounding rock. His labours were rewarded by the successful extrication of the specimen, which he conveyed in triumph to his house. This extraordinary discovery soon became the subject of general conversation, and upon reaching the ears of the Canon of the cathedral which stands on the mountain, excited in that functionary a determination to claim the fossil, in right of being lord of the manor; and he unfortunately succeeded, after a long and harassing lawsuit, in obtaining this precious relic. It remained for years in his possession, and Hoffman died without regaining his treasure, or receiving any compensation. At length the French revolution broke out, and the armies of the republic advanced to the gates of Maestricht. The town was bombarded; but at the suggestion of the committee of savans who accompanied the French troops to select their share of plunder, the artillery was not suffered to bombard that part of the city in which the celebrated fossil was known to be preserved. In the mean time, the Canon of St. Peter's, shrewdly suspecting the reason why such peculiar favour was shown to his residence, removed the specimen, and concealed it in a vault; but when the city was taken, the French authorities compelled him to give up his ill-gotten prize, which was immediately transmitted to the Jardin des Plantes, at Paris, where it still forms one of the most striking objects in that magnificent collection.[130]

[Footnote 130: Faujus St. Fond, in whose beautiful work on the fossils of St. Peter's Mountain the above account is given, remarks with much sang froid, "La _justice_, quoique tardive, arrive enfin avec le tems!" The reader will probably think that although the Canon was justly despoiled of his ill-gotten treasure, the French _savans_ were a very equivocal personification of _Justice_!]

The beautiful model of this most interesting fossil in the British Museum, was presented to me by Baron Cuvier. It is four and a half feet long, and two and a half wide; it consists of the jaws, with teeth, palatal bones, and the tympanic bone, or _os quadratum_, a bone possessed by reptiles, as well as birds, and in which the auditory cells are contained. There are likewise some fine portions of jaws, with teeth, in the British Museum, presented by Camper. The original animal was probably a terrestrial reptile, holding an intermediate place between the Monitors and Iguanas. It was about twenty-five feet long.

I discovered, many years since (1820), some vertebræ in the chalk near Lewes, which closely resemble the corresponding bones of the Mosasaurus, and in all probability belong to another species. In the cretaceous strata of New Jersey, Dr. Harlan found and described, and my friend. Dr. Morton, of Philadelphia, sent me, in 1834, teeth which cannot be distinguished from those of Maestricht. Vertebræ, and other bones, have since been obtained from the same deposits by Professor Rogers, and described by Professor Owen in the Geological Journal.

XVI. Fossil Reptiles. Although when Mr. Parkinson's work was published many fossil bones and teeth of reptiles had been discovered in various parts of England, yet the abundance and variety, and the extraordinary modification of form and structure of this class of vertebrated animals, which prevailed throughout the secondary geological formations, were not for a moment suspected. The few examples of the remains of fossil reptiles described by Mr. Parkinson, serve to mark the degree of knowledge which then existed respecting a department of palæontology that rapidly acquired an importance and interest unsurpassed by any other branch of fossil osteology.

The announcement of the founder of palæontology,[131] that there was a period when the lakes and rivers of our planet were peopled by reptiles, and cold-blooded oviparous quadrupeds of appalling magnitude were the principal inhabitants of the dry land; when the seas swarmed with saurians, exclusively adapted for a marine existence, and the regions of the atmosphere were traversed by winged lizards instead of birds; was an enunciation so novel and startling, as to require all the prestige of the name of Cuvier, to obtain for it any degree of attention and credence, even with those who were sufficiently enlightened to admit, that a universal deluge would not account for the physical mutations which the surface of the earth and its inhabitants had, in the lapse of innumerable ages, undergone.

[Footnote 131: In the "Ossemens Fossiles;" tom. v. Reptiles Fossiles.]

Subsequent discoveries have established the truth of this proposition to an extent beyond what even its promulgator could have surmised; and the "_Age of Reptiles_" is now admitted into the category of established facts.

During the incalculable ages which the formation of the various systems of secondary strata must have comprised, we find no evidence in the fossils hitherto observed, of the existence of birds and mammalia, as the characteristic types of the faunas of the dry land. On the contrary, throughout the immense accumulations of the spoils of the ancient islands and continents, amidst innumerable relics of reptiles of various orders and genera, a few jaws and bones of two or three kinds of extremely small marsupials, and the bones of a species of wader, are the sole indications of the presence of the two grand classes of Aves and Mammalia, which now constitute the chief features of the terrestrial zoology of almost all countries.

The earliest indications of air-breathing vertebrata in the ancient secondary formations are those of small saurian reptiles in the carboniferous strata; a few vestiges occur in the succeeding group, the Permian. In the next epoch, the Triassic, colossal Batrachians (_Labyrinthodonts_) appear; and on some of the strata of this formation are the footmarks of numerous bipeds, presumed to be those of birds; but at present the evidence of the bones of the animals that made those imprints is required to establish the hypothesis.

In the succeeding eras, the Lias, Oolite, Wealden, and Cretaceous, swarms of reptiles of numerous genera and species everywhere prevail; reptiles fitted to fly through the air, to roam over the land, to inhabit the lakes, rivers, and seas; and yet not one identical with any existing forms! These beings gradually decline in numbers and species as we approach the close of the secondary periods, and are immediately succeeded in the eocene epoch, by as great a preponderance of warm-blooded vertebrata--birds and mammalia--as exists at the present time; and an equal decadence in the class of reptiles. With the Cretaceous Formation the "Age of Reptiles" may be said to terminate.

XVII.--Fossil Reptiles of the Wealden. _The Iguanodon._ The fluviatile deposits (termed _Wealden_), which in the south-east of England, and in the north of Germany, are intercalated between the oolitic and cretaceous formations, abound in the bones of terrestrial, fresh-water, and marine reptiles, comprising some of the most colossal land-saurians which have hitherto been brought to light. These remains belong to various genera of Chelonians, Saurians, and Crocodilians; and with these are associated those of flying lizards (_Pterodactyles_), Plesiosauri, gigantic whale-like reptiles (_Cetiosauri_), and of other oviparous quadrupeds of unknown species and genera.

The occurrence of fossils of this nature in the strata forming the districts denominated the Wealds of Sussex and Kent, was first brought under the notice of geologists in 1822, in my work on the "Fossils of the South Downs," in which the remains of several unknown reptiles were described; and among them the teeth and bones of that extraordinary herbivorous lizard, the _Iguanodon_, on which I am induced to offer a few observations in this place; the recent discovery of some previously undetermined parts of the skeleton, having materially elucidated the structure and economy of the original.[132]

[Footnote 132: The following is the description of the specimens first discovered, given in the "Fossils of the South Downs; or, Illustrations of the Geology of Sussex," 1 vol. 4to. 1822: "Incisors and molar teeth evidently belonging to the same species of animal: they differ from any previously known; the masticating surface is perfectly smooth and rather depressed in the centre; these teeth consist of the crown only, and are quite solid. An incisor tooth 1.3 inch long Is slightly bowed and smooth on its inner surface; but it has externally a ridge which extends longitudinally down the front. Its sides are angular and the edges finely crenated." From the resemblance of these teeth in their general form to those of the Iguana, a common land lizard in the West Indies, I subsequently proposed the name of _Iguanodon_ (implying an animal having teeth like the Iguana) for the fossil reptile. The teeth of an Iguana four or five feet long are not larger than those of a mouse; the Iguanodon's teeth are as large as the incisors of the rhinoceros. The Iguana's teeth, when used, are chipped off at the points, no existing reptile being capable of performing mastication; the teeth of the Iguanodon, on the contrary, are ground down like the worn molars of herbivorous mammalia, as I pointed out in my first memoir in the Philos. Trans. 1825.]

Since the first announcement of the discovery of the remains of the Iguanodon, vast quantities of bones belonging to a great number of individuals of all ages have been collected; but until a few years since, not a vestige of the jaws had been observed, notwithstanding the most diligent research. In the early part of the year 1848, I was surprised and highly gratified by receiving from Capt. Lambart Brickenden (at that time a personal stranger to me), who then resided at Warminglid, near Cuckfield, in Sussex, the greater part of the right side (or _ramus_) of the lower jaw, with several successional teeth in their natural position, of an adult Iguanodon.[133] See p. 202.

[Footnote 133: This beautiful and most instructive specimen is now in my possession; it is figured of the natural size in Philos. Trans. Part ii. for 1848, Plate XVI., as well as the portion of upper jaw in the British Museum, Plate XIX. The character of the upper and lower teeth of the Iguanodon are well represented in Plate XVIII. of the same memoir.

A specimen very similar to that discovered by Capt. Brickenden, but of a young individual, was found soon afterwards in a quarry near Horsham; but I was not allowed the privilege of figuring or describing it!]

In the course of last summer I obtained a very instructive fragment of the middle part of the right ramus of the lower jaw of a much larger Iguanodon, found by Mr. Fowlestone, with some enormous bones of the extremities, in the Wealden strata of the Isle of Wight. A portion of the upper jaw (without teeth) was discovered some years since in Tilgate Forest, and is deposited, with the whole of the collection I formed at Brighton, in the gallery of organic remains of the British Museum. These three specimens are the only parts of the jaws of the Iguanodon, with the exception of a fragment of the angular bone, that I have had the opportunity of examining. The other portions of the skeleton hitherto discovered are the following: the tympanic bone;[134] cervical, dorsal, lumbar, and caudal vertebræ, and chevron bones; ribs; the iliac bones, and sacrum composed of six anchylosed vertebræ;[135] the coracoid, scapula and clavicles; humerus, radius? metacarpals; femur, tibia and fibula, metatarsals and ungueals. The cranium, carpals, and tarsals, have not been discovered.

[Footnote 134: This may or may not belong to the Iguanodon: no tympanic bone has been found in such connexion with other parts of the skeleton as to afford certain proof that this maxillary element is referable to the Iguanodon.]

[Footnote 135: In the Megalosaurus, the sacrum consists of five anchylosed vertebræ.]

With the exception of the assemblage of bones promiscuously grouped together in a block of _Kentish rag_ (of the greensand formation), found in a quarry near Maidstone, by Mr. Bensted,[136] a few connected caudal vertebræ, and two or three instances in which a femur, tibia, and fibula and some metatarsals, were found in contiguity, all the bones were isolated. They have been obtained from the quarries in St. Leonard's and Tilgate Forests, near Loxwood, Rusper, Horsham, Cuckfield, and Battel; and from the cliffs at Hastings, and in Sandown, and Brixton, and Brook Bays, on the southern shore of the Isle of Wight.

[Footnote 136: This most instructive specimen is in a glass-case on the floor near the window, in the middle room of the Gallery of Organic Remains in the British Museum. All the Wealden reptilian remains of a large size, collected by me when residing in Sussex, are in the upright glass cases in the same apartment.]

So anomalous is the osteology of the Iguanodon compared with that of existing saurians, that from my discovery of the first vestige of this reptile--a fragment of a tooth--thirty years ago, to the recent important acquisition of the jaws, I have had to contend with the opposition of eminent naturalists, who have refused assent to the physiological inferences suggested by the specimens which were from time to time brought to light, because the modifications of structure in a colossal herbivorous reptile, essentially differed from the hypothetical archetype skeleton of the class to which it belonged. When the first discovered teeth were shown to Baron Cuvier, he pronounced them to be the incisors of a Rhinoceros; the metatarsals, those of a Hippopotamus; the fragment of a femur, with a medullary canal, that of some large mammalian. But the candour and liberality of the founder of Palæontology were worthy of his transcendent genius; upon receiving further evidence, he immediately acknowledged the error, and expressed his conviction that the teeth and bones belonged to an herbivorous reptile more extraordinary than any that had previously been brought under his notice.[137]

[Footnote 137: See Cuvier's Ossemens Fossiles, tom. v. part. ii. It is much to be wished that those who aspire to emulate this great man in scientific fame, would also endeavour to imitate him in the yet nobler attributes of his character. It is stated by Professor Owen, in Brit. Assoc. Reports on Fossil Reptiles, that the bones of the Iguanodon were interpreted by me with the aid of Cuvier and Clift. This is a mistake. Baron Cuvier died before I had obtained any considerable portion of the skeleton; and neither Mr. Clift nor Mr. Owen at that time could afford me any assistance in determining the nature of the isolated bones I occasionally brought to the Hunterian Museum for comparison. Any aid I ever received in my investigations is most fully acknowledged in my works.]

Even the lower jaw, which presents characters so peculiar as to admit, as I conceive, of but one interpretation--that enunciated in my memoir on the teeth and jaws of the Iguanodon,[138]--has been adduced as affording a signal instance of the incorrectness of my physiological deductions. And why? Because in the entire class of living reptiles there is not a single species that has cheeks and flexible lips, which, according to my view of the subject, the Iguanodon must have possessed. But I do not hesitate to affirm that the structure and arrangement of the teeth, and the mammalian character of the bones of the extremities, are in perfect accordance with my exposition of the probable structure and functions of the maxillary organs of the original. The naturalists who advance these objections, forget that among the existing mammalia there is one genus, the _Ornithorhynchus_, or Duck-billed Platypus, that exhibits as striking a deviation from the typical maxillary structure of its class, as does the Iguanodon. If before the discovery of New Holland the jaw-bones of the Ornithorhynchus had been found in a fossil state in the strata of Tilgate Forest, and I had ventured to infer that the original, though a true mammalian, and giving suck to its young, had the extremities of the jaws covered with flat horny beaks, like those of a duck, instead of with the fleshy lips and integuments which are the peculiar attributes of its class, what censures would not my temerity have called forth! We cannot too often be reminded of the profound remark of William Penn: "Experience, which is continually contradicting theory, is the only test of truth."

[Footnote 138: See Philosophical Transactions, Part II. 1848.]

The following are the physiological inferences relating to the structure and habits of the Iguanodon, which Dr. Melville and myself conceive our investigations have established: the discovery of the cranium, and of perfect examples of the upper and lower jaws with both successional and mature molars in their natural position, may modify, but, we believe, will in no material respect invalidate these conclusions.

In instituting a comparison between the maxillary organs of the Iguanodon, and those of the existing herbivorous lizards, we are at once struck with their remarkable deviation from all known types in the class of reptiles. In the _Amblyrhynchi_ (of the Galapagos Islands), the most exclusively vegetable feeders of the Saurian order, the alveolar process beset with teeth is continued round the front of the mouth: the junction of the two rami of the lower jaw at the symphysis presenting no edentulous interval whatever, the lips not being more produced than in other reptiles; but this creature only bruises its food; it cannot grind or masticate it. In fact, the edentulous, expanded, scoop-shaped, procumbent symphysis of the lower jaw of the Iguanodon, has no parallel among either recent or fossil reptiles; and we seek in vain for organs at all analogous, except among the herbivorous mammalia. The nearest approach is to be found in certain _Edentata_; as for example in the _Cholæpus didactylus_, or Two-toed Sloth, in which the anterior part of the lower jaw is destitute of teeth, and much prolonged. The correspondence is still closer in the extinct gigantic _Mylodons_, in which the symphysis resembles the blade of a turf-spade, and has no traces of incisor sockets; and were not this part of the jaw elevated vertically in front, and the two sides confluent, it would present the very counterpart of that of the Iguanodon. The great number and size of the vascular foramina distributed along the outer side of the dentary bone in the Wealden reptile, and the magnitude of the anterior outlets which gave exit to the vessels and nerves that supplied the front of the mouth, indicate the great development of the integuments and soft parts with which the lower jaw was invested.

The sharp ridge bordering the deep groove of the symphysis, in which there are also several foramina, evidently gave attachment to the muscles and integuments of the under lip; and there are strong reasons for supposing that the latter was greatly produced, and capable of being protruded and retracted so as to constitute, in conjunction with a long extensile tongue, a suitable instrument for seizing and cropping leaves and branches, which, from the construction of the teeth, we may infer was the food of the Iguanodon.