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Page GEOLOGICAL INTRODUCTION 3

TOXODON PLATENSIS, Description of Cranium 16 of Lower Jaw and Teeth 29

MACRAUCHENIA PATACHONICA, Cervical Vertebrae 35 Lumbar Vertebrae 40 Scapula 43 Antibrachium and Fore-foot 44 Femur 48 Tibia, Astragalus, and Metatarsal Bone 50

GLOSSOTHERIUM, Fragment of Cranium 57

MYLODON DARWINII, Lower Jaw and Teeth 63

SCELIDOTHERIUM LEPTOCEPHALUM, Cranium and Teeth 73 Vertebral Column 84 Bones of the Extremities 88

MEGALONYX JEFFERSONII, Lower Jaw 99

MEGATHERIUM CUVIERI, Cranium and Teeth 100

TESSELATED ARMOUR AND BONES, large Edentata 106

MASTODON ANGUSTIDENS, Cuv. 108

EQUUS, Molar Teeth 108

CTENOMYS PRISCUS, and a large Rodent 109

Geological contemporaneity of preceding extinct Mammalia 111

LIST OF PLATES.

PREFACE.

His Majesty's ship, Beagle, under the command of Captain FitzRoy, was commissioned in July, 1831, for the purpose of surveying the southern parts of America, and afterwards of circumnavigating the world. In consequence of Captain FitzRoy having expressed a desire that some scientific person should be on board, and having offered to give up part of his own accommodations, I volunteered my services; and through the kindness of the hydrographer, Captain Beaufort, my appointment received the sanction of the Admiralty. I must here, as on all other occasions, take the opportunity of publicly acknowledging with gratitude, the obligation under which I lie to Captain FitzRoy, and to all the Officers on board the Beagle, for their constant assistance in my scientific pursuits, and for their uniform kindness to me throughout the voyage. On my return to England, I found myself in possession of a large collection of specimens in various branches of natural history; but from the great expense necessary to secure their publication, I was without the means of rendering them generally serviceable.

The Presidents of the Linnean, Zoological, and Geological Societies, having given me their opinion respecting the utility to be derived from publishing these materials, I addressed a letter to the Right Honourable the Chancellor of the Exchequer informing him of the circumstances under which I hoped that I might venture to solicit the aid of Government. In reply, I received a communication announcing to me that the Lords of the Treasury, from their readiness to promote Science, were willing, under certain conditions, to give me the most liberal assistance.

"SIR,

"It having been represented to the Lords Commissioners of Her Majesty's Treasury, from various quarters, that great advantage would be derived to the Science of Natural History, if arrangements could be made for enabling you to publish, in a convenient form, and at a cheap rate, the result of your labours in that branch of science, my Lords will feel themselves justified in giving their sanction to the application of a sum, not exceeding in the whole one thousand pounds, in aid of such a publication; upon the clear and distinct understanding that the Work should be published, and the plates engraved, in such a manner as to be most advantageous to the Public at large, upon a plan of arrangement to be previously submitted to, and sanctioned by the Board, after consultation with those persons, who, from their attainments in this branch of science, are the most capable of advising their Lordships thereupon; and that the payments on account of the said sum of one thousand pounds are to be made to you from time to time, on a certificate that such progress has been made in the engravings, in accordance with the plan previously approved of, as to justify the issue then applied for. My Lords have therefore directed me to communicate to you the views they entertain upon this subject; and to apprize you that they will be prepared to act in conformity with their arrangement, upon learning from you that you are ready to proceed with the Work upon the principles above laid down, and upon receiving from you a statement of the manner in which you think the Work should be published, and the plates engraved, so as most effectually to accomplish the object my Lords have in view, in sanctioning the payment from the Public Funds, in aid of the expenses of the Work in question.

"I remain, "Sir, Your Obedient Servant, "A. Y. SPEARMAN."

The object of the present Work is to give descriptions and figures of undescribed and imperfectly known animals, both fossil and recent, together with some account, in the one case, of their geological position, and in the other of their habits and ranges. As I do not possess the knowledge requisite for such an undertaking, and as I am, moreover, particularly engaged in preparing an account of the geological observations, made during the voyage, several gentlemen have most kindly undertaken different portions of the Work. Besides the very great advantage insured in thus enlisting the attainments of these Naturalists in the several departments of science, to which they have paid most attention, a great delay is avoided by adopting this method of publication, which must otherwise have been incurred before the materials could have been made known.

An Account of the Voyage, drawn up by Captain FitzRoy, being on the point of publication, I shall not in this Work enter on any minute details respecting the countries which were visited, but shall merely give a sketch of the geology in the introduction to the part containing Fossil Mammalia, and a brief geographical notice in that attached to the account of existing animals. At the conclusion of this Work, I shall endeavour to place together the leading results in the natural history of the different countries, from which the collections were procured. I may here state that Mr. Owen has undertaken the description of the Fossil Mammalia; Mr. Waterhouse, the Recent Mammalia; Mr. Gould, the Birds; Mr. Bell, the Reptiles; and the Rev. L. Jenyns, the Fish. Whatever assistance I may obtain in the invertebrate classes, will be noticed in their respective places. The specimens have been presented to the various public museums, in which it was thought they would be of most general service: mention will be made in each part where the objects described have been deposited.

FOSSIL MAMMALIA,

Described by

RICHARD OWEN, ESQ. F.R.S. F.G.S. F.L.S.

PROFESSOR OF ANATOMY AND PHYSIOLOGY TO THE ROYAL COLLEGE OF SURGEONS IN LONDON; CORRESPONDING MEMBER OF THE ROYAL ACADEMY OF SCIENCES OF BERLIN; OF THE ROYAL ACADEMY OF MEDICINE, AND PHILOMATHIC SOCIETY OF PARIS; OF THE ACADEMY OF SCIENCES OF PHILADELPHIA, MOSCOW, ERLANGEN.

WITH

A GEOLOGICAL INTRODUCTION,

BY CHARLES DARWIN, ESQ. M.A. F.G.S. &c. &c.

CORRESPONDING MEMBER OF THE ZOOLOGICAL SOCIETY.

GEOLOGICAL INTRODUCTION.

BY MR. DARWIN.

Mr. Owen having undertaken the description of the fossil remains of the Mammalia, which were collected during the voyage of the Beagle, and which are now deposited in the Museum of the College of Surgeons in London, it remains for me briefly to state the circumstances under which they were discovered. As it would require a lengthened discussion to enter fully on the geological history of the deposits in which these remains have been preserved, and as this will be the subject of a separate work, I shall here only give sufficient details, for the reader to form some general idea of the epoch, at which these animals lived,--of their relative antiquity one to the other,--and of the circumstances under which their skeletons were embedded. All the remains were found between latitudes 31? and 50? on the eastern side of South America. The localities may conveniently be classed under three divisions, namely--the Provinces bordering the Plata; Bahia Blanca situated near the confines of Northern Patagonia; and Southern Patagonia.

The first division includes an enormous area, abounding with the remains of large animals. To the eastward and southward of the great streams, which unite to form the estuary of the Plata, those almost boundless plains extend, which are known by the name of the Pampas. Their physical constitution does not vary over a wide extent;--the traveller may pass for many hundred miles on a level surface, without meeting with a single pebble, or discovering any change in the nature of the soil. The formation consists of a reddish argillaceous earth, generally containing irregular concretions of a pale brown, indurated marl. This stone, where most compact, is traversed by small linear cavities, and in several respects resembles the less pure fresh-water limestones of Europe. The concretions not unfrequently become so numerous, that they unite and form a continuous stratum, or even the entire mass.

In the province of Banda Oriental , and in part of that of Entre Rios, the land, though very low and level, has a foundation of granitic and other primary rocks. These older formations are partially covered, in most parts, by a reddish earthy mass containing a few small calcareous concretions; while in other parts, they are concealed by more regular strata, of indurated marl passing into limestone, of conglomerates, and ferruginous sandstone. The entire formation probably belongs to the same epoch with that of the Pampas deposit. In the earthy mass, even where it is of little thickness, and where it might readily be mistaken for detritus produced from the underlying granites, remains of large quadrupeds have several times been discovered.

On the shores of the Plata and in the neighbouring districts, proofs of a change of level having taken place between the land and the water within a recent period, may be observed. Both near Monte Video and Colonia del Sacramiento, beds of shells are lying on the beach at the height of several feet above the present tidal action. Near Maldonado I saw estuary shells of recent species embedded in clay, and raised above the level of a neighbouring fresh-water lake.

After these facts we may feel certain, that at a period not very remote, a great bay occupied the area both of the Pampas and of the lower parts of Banda Oriental. Into this bay the rivers which are now united in the one great stream of the Plata, must formerly have carried down the carcasses of the animals, inhabiting the surrounding countries; and their skeletons would thus become entombed in the estuary mud which was then tranquilly accumulating. Nothing less than a long succession of such accidents can account for the vast number of remains now found buried. As their exposure has invariably been due to the intersection of the plain by the banks of some stream, it is not making an extravagant assertion, to say, that any line whatever drawn across the Pampas would probably cross the skeleton of some extinct animal.

At Bajada, a passage, as I have stated, may be traced upwards from the beds containing marine shells, to the estuary mud with the bones of land animals. In another locality a bed of the same mineralogical nature with the Pampas deposit, underlies clay containing large oysters and other shells, apparently the same with those at Bajada. We may, therefore, conclude that at the period when the Arca, Venus, and Oyster were living, the physical condition of the surrounding country was nearly the same, as at the time when the remains of the mammalia were embedded; and therefore that these shells and the extinct quadrupeds probably either co-existed, or that the interval between their respective existences was, in a geological point of view, extremely short. In this part of South America there is reason to believe that the movements of the land have been so regular, that the period of its elevation may be taken as an element in considering the age of any deposit. The circumstance, therefore, that the beds immediately bordering the Plata, contain very nearly the same species of molluscs, with those now existing in the neighbouring sea, harmonizes perfectly with the more ancient tertiary character of the fossils underlying the Pampas deposit at Bajada, situated at a greater height, and at a considerable distance in the interior. I feel little doubt that the final extinction of the several large quadrupeds of La Plata did not take place, until the time when the sea was peopled with all, or nearly all, its present inhabitants.

Bahia Blanca, situated in latitude 39?, and about 250 miles south of the Plata, constitutes the second district, in which I found the remains of quadrupeds. This large bay is nearly surrounded by very low land, on which successive lines of sand dunes mark in many parts the retreat of the water. At some distance inland a formation of highly indurated marl, passing into limestone, forms an escarpment. Beyond this, rocks of the same character extend over a wide and desolate plain, which rises towards the flanks of the distant mountain of the Sierra de la Ventana, composed of quartz. On the low shores of this bay, only two places occur, where any section of the strata can be seen; and at both of these I found fossil remains.

At Monte Hermoso, a line of cliff of about 120 feet in height, consists in the upper part of a stratum of soft sandstone with quartz pebbles; and in the lower of a red argillaceous earth, containing concretions of pale indurated marl. This lower bed has the same mineralogical character with the Pampas deposit; and possibly may be connected with it. The embedded bones were blackened, and had undergone more chemical change than in any other locality, which I examined. With the exception of a few large scattered bones, the remains seemed to belong chiefly to very small quadrupeds.

In another part of the bay, called Punta Alta, about eighteen miles from Monte Hermoso, a very small extent of cliff, about twenty feet high, is exposed. The lower bed seen at ebb tide, extends over a considerable area; it consists of a mass of quartz shingle, irregularly stratified, and divided by curved layers of indurated clay. The pebbles are cemented together by calcareous matter, which results, perhaps, from the partial decomposition of numerous embedded shells. In this gravel the remains of several gigantic animals were extraordinarily numerous. The cliff, in the part above high-water mark, is chiefly composed of a reddish indurated argillaceous earth; which either passes into, or is replaced by, the same kind of gravel, as that on which the whole rests. The earthy substance is coarser than that at Monte Hermoso, and does not contain calcareous concretions. I found in it a very few fragments of shells, and part of the remains of one quadruped.

From the bones in one of the skeletons, and likewise from those in part of another, being embedded in their proper relative positions, the carcasses of the animals, when they perished, were probably drifted to this spot in an entire state. The gravel, from its stratification and general appearance, exactly resembles that which is every day accumulating in banks, where either tides or currents meet; and the embedded shells are of littoral species. But from the skeleton, in one instance, being in a position nearly undisturbed, and from the abundance of serpulae and encrusting corallines adhering to some of the bones, the water, at the time of their burial, must have been deeper than at present. This conclusion might also have been inferred from the fact, that in the neighbouring cliff the same bed, with its shells, has been uplifted some yards above high-water mark. On the coast to the southward abundant proofs occur, of a recent elevation of the continent. In the gravel, nearly all the pebbles are of quartz, and have originally proceeded from the lofty range of the Ventana, distant between forty and fifty miles. Besides the pebbles of quartz, there are a few irregular masses of the same indurated marl, of which the escarpment of the neighbouring great plain is composed. Hence the gravel beds must have been deposited, when the plain existed as dry land; and on it probably those great animals once lived, of which we now find only the remains. The indurated marl forming the plain, is the same kind of rock with that occurring over a wide extent of the Pampas; and there is no reason to doubt, they are parts of one great formation. Nevertheless, the gravel bed of Bahia Blanca, although subsequent to the calcareous formation, may be of the same age with those parts of the Pampas, which stand at a low level near the Plata. For on this whole line of coast, I believe, as the land has continued rising, fresh littoral deposits have been formed; and each of these would often owe part of its materials to the degradation of the one last elevated.

With respect to the relative age of the Monte Hermoso and Punta Alta beds, it is not possible to speak decidedly. A certain degree of similarity in the nature of the strata containing quartz pebbles, and those of the reddish indurated earth; and the short distance between the two localities, would indicate that no long interval had intervened. The beds at Monte Hermoso, certainly were deposited more tranquilly, and probably in a deeper sea; so that even skeletons of animals, no larger than rats, have been perfectly preserved there. In some parts of the surrounding country, obscure traces of a succession of step-formed terraces may be observed; and each of these indicates a period of repose during the elevation of the land, at which time the strata previously existing were worn away, and fresh matter deposited. The Monte Hermoso beds were, perhaps, formed during one such interval, anterior to the accumulation of the shingle bank at Punta Alta.

Mr. G. Sowerby, who has been good enough to examine the shells which were found with the remains of the quadrupeds, has given me the following list.

I may add that a fossil encrusting coralline is the same with one now living in the bay.

Of these shells it is almost certain that twelve species are absolutely identical with existing species; and that four more are perhaps so; the doubt partly arising from the imperfect condition of the specimens. Of the seven re afloop van den veldtocht aan hem geen aandacht konden schenken. Die slag trof Columbus geweldig, maar wierp hem evenwel niet ter neer. Nog kon zijn onbedwingbare geest er niet tot wanhoop door gebracht worden. Hij zette zich rustig neer, en ging na, welk hulpmiddel hij nu kon aangrijpen.

Men leefde in een tijd van feudale macht en welvaart. De Spaansche bergen waren bezaaid met de sterke kasteelen van hertogen en baronnen. Columbus wendde zich tot den hertog van Medina Sidonia. Deze machtige heer, wiens kasteel een bijna onneembare vesting was, en geheel uit ijzer en steen bestond, behoorde tot den hoogsten adel in Europa. Wat de glans van zijn hof en levenswijze betrof, kon hij met koningen wedijveren. Uit eigen middelen verschafte hij de vorsten een heel leger ruiters, honderd oorlogsschepen en een groote som geld. De schitterende onderneming, die Columbus wilde doen, viel voor een poos in den smaak van den hertog, doch bij nader inzien verwierp hij het plan als den droom van een dweper.

Men zegt, dat Columbus toen bij den hertog van Medina Celi ging aankloppen. Hier werd hij aanvankelijk gunstig ontvangen. De hertog stond op het punt drie of vier schepen voor den tocht uit te rusten, maar hij haalde zich in het hoofd, dat de Spaansche vorsten het hem euvel konden duiden, wanneer hij zulk een grootsche onderneming op eigen kosten deed. Daarom liet hij Columbus gaan.

Zich zoo bedrogen ziende, besloot Columbus zijn geluk bij het Fransche hof te beproeven. Hij had nu een aantal invloedrijke en vermogende vrienden, die ongetwijfeld hun beurs voor zijn bescheiden eischen zouden openen. V??r hij op zijn lange reis naar de Fransche hoofdstad de Pyrenee?n overtrok, bezocht hij eerst nog zijn zoon Diego in het klooster van La Rabida, bij Palos. Hij legde de reis te voet of op een muilezel gezeten af. Hadden zijn vrienden hem al een beetje geld gegeven, zeker is het, dat hij de grootste zuinigheid noodig achtte. Hij moest nog een lange en kostbare reis doen, en het was nog onzeker, hoe hij aan het trotsche hof van den Franschen koning zou worden ontvangen.

In een eenvoudig gewaad, door de reis met stof bedekt, stond Columbus v??r de deur van het klooster. Maar noch stof noch kale kleeren konden de aangeboren waardigheid van den man verbergen. Hij was van nature een edelman, die, om zijn aanspraken te rechtvaardigen, den glans van kostbare kleeren niet noodig had. Sedert hij voor de eerste maal aan de deur van dat klooster stond, om wat drinken voor zijn kind te vragen, waren er zeven jaren van aanhoudende inspanning en teleurstelling voorbij gegaan. Deze verdrietelijkheden en inspanningen hadden zijn lichaam gekromd en zijn haren vergrijsd. Zijn wangen waren gerimpeld, wat zoo licht plaats heeft, wanneer men teleurgesteld wordt en zwaar moet denken.

De waardige prior van het klooster ontving den vermoeiden avonturier met ware, broederlijke vriendelijkheid. Hij was geheel en al overtuigd geworden, dat Columbus' plannen verstandig waren, en de dadelijke en ernstige aandacht van het Spaansche hof verdienden. Toen hij de zekerheid had, dat Columbus over een bezoek aan Frankrijk dacht, ontwaakte zijn vaderlandsliefde en maakte hij zich zeer beangst, dat Spanje den roem van de groote onderneming derven zou. Dadelijk liet hij den geleerden arts ontbieden, van wien wij vroeger spraken, en deelde hem zijn vrees mee. Ook werden vele andere invloedrijke vrienden uitgenoodigd, om met Columbus over die allergewichtigste zaak te beraadslagen, welke den prior voorkwam zoo belangrijk voor den roem van Spanje te zijn.

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