the attached valve must have remained exposed long enough to allow of the growth of the whole coralline, since corallines do not live imbedded in mud. The progress of knowledge may one day enable us to deduce from such facts as these the maximum rate at which the chalk can have accumulated, and thus to arrive at the minimum duration of the chalk period. Suppose that the valve of the Crania, upon which a coralline has fixed itself in the way just described, is so attached to the seaurchin that no part of it is more than an inch above the face upon which the seaurchin rests. Then, as the coralline could not have fixed itself if the Crania had been covered up with chalk mud, and could not have lived had itself been so covered, it follows that an inch of chalk mud could not have accumulated within the time between the death and decay of the soft parts of the sea-urchin and the growth of the coralline to the full size which it has attained. If the decay of the soft parts of the sea-urchin, the attachment, growth to maturity, and decay of the Crania, and the subsequent attachment and growth of the coralline, took a year (which is a low estimate enough), the accumulation of the inch of chalk must have taken more than a year; and the deposit of a thousand feet of chalk must consequently have taken more than twelve thousand years. The foundation of all this calculation is, of course, a knowledge of the length of time the Crania and the coralline needed to attain their full size; and on this head precise knowledge is at present wanting. But there are circumstances which tend to show that nothing like an inch of chalk has accumulated during the life of a Crania; and, on any probable estimate of the length of that life, the chalk period must have had a much longer duration than that thus roughly as signed to it. Thus, not only is it certain that the chalk is the mud of an ancient sea-bottom, but it is no less certain that the chalk sea existed during an extremely long period, though we may not be prepared to give a precise estimate of the length of that period in years. The relative duration is clear, though the absolute duration may not be definable. The attempt to affix any precise date to the period at which the chalk sea began or ended its existence is baffled by difficulties of the same kind. But the relative age of the cretaceous epoch may be determined with as great ease and certainty as the long duration of that epoch. You will have heard of the interesting discoveries recently made, in various parts of Western Europe, of flint implements, obviously worked into shape by human hands, under circumstances which show conclusively that man is a very ancient denizen of these regions. It has been proved that the old populations of Europe, whose existence has been revealed to us in this way, consisted of savages, such as the Esquimaux are now; that, in the country which is now France, they hunted the reindeer, and were familiar with the ways of the mammoth and the bison. The physical geography of France was in those days different from what it is now the river Somme, for instance, having cut its bed a hundred feet deeper between that time and this; and it is probable that the climate was more like that of Canada or Siberia, than that of Western Europe. The existence of these people is forgotten even in the traditions of the oldest historical nations. The name and fame of them had utterly vanished until a few years back; and the amount of physical change which has been effected since their day renders it more than probable that, venerable as are some of the historical nations, the workers of the chipped flints of Hoxne or of Amiens are to them as they are to us in point of antiquity. But, if we assign to these hoar relics of long vanished generations of men the greatest age that can possibly be claimed for them, they are not older than the drift, or boulder clay, which, in comparison with the chalk, is but a very juvenile deposit. You need go no further than your own sea-board for evidence of this fact. At one of the most charming spots on the coast of Norfolk, Cromer, you will see the boulder clay forming a vast mass, which lies upon the chalk, and must consequently have come into existence after it. Huge boulders of chalk are, in fact, included in the clay, and have evidently been brought to the position they now occupy by the same agency as that which has planted blocks of syenite from Norway side by side with them. The chalk, then, is certainly older than the boulder clay. If you ask how much, I will again take you no further than the same spot upon your own coasts for evidence. I have spoken of the boulder clay and drift as resting upon the chalk. This is not strictly true. Interposed between the chalk and the drift is a comparably insignificant layer, containing vegetable matter. But that layer tells a wonderful history. It is full of stumps of trees standing as they grew. Fir-trees are there with their cones, and hazel-bushes with their nuts; there stand the stools of oak and yew trees, beeches and alders. Hence this stratum is appropriately called the "forest-bed." It is obvious that the chalk must have been upheaved and converted into dry land before the timber trees could grow upon it. As the bolls of some of these trees are from two to three feet in diameter, it is no less clear that the dry land thus formed remained in the same condition for long ages. And not only do the remains of stately oaks and well-grown firs testify to the duration of this condition of things, but additional evidence to the same effect is afforded by the abundant remains of elephants, rhinoceroses, hippopotamuses, and other great wild beasts, which it has yielded to the zealous search of such men as the Rev. Mr. Gunn. When you look at such a collection as he has formed, and bethink you that these elephantine bones did veritably carry their owners about, and these great grinders crunch in the dark woods of which the forest-bed is now the only trace, it is impossible not to feel that they are as good evidences of the lapse of time as the annual rings of the tree-stumps. Thus there is a writing upon the wall of cliffs at Cromer, and whoso runs may read it. It tells us, with an authority which cannot be impeached, that the ancient sea-bed of the chalk sea was raised up and remained dry land until it was covered with forest, stocked with the great game whose spoils have rejoiced your geologists. How long it remained in that condition cannot be said; but "the whirligig of time brought its revenges" in those days as in these. That dry land, with the bones and teeth of generations of long-lived elephants hidden away among the gnarled roots and dry leaves of its ancient trees, sank gradually to the bottom of the icy sea, which covered it with huge masses of drift and boulder clay. Sea-beasts, such as the walrus, now restricted to the extreme north, paddled about where birds had twittered among the topmost twigs of the fir-trees. How long this state of things endured we know not, but at length it came to an end. The upheaved glacial mud hardened into the soil of modern Norfolk. Forests grew once more, the wolf and the beaver replaced the reindeer and the elephant; and at length what we call the history of England dawned. Thus you have, within the limits of your own county, proof that the chalk can justly claim a very much greater antiquity than even the oldest physical traces of mankind. But we may go further, and demonstrate, by evidence of the same authority as that which testifies to the existence of the fa ther of men, that the chalk is vastly older than Adam himself. The Book of Genesis informs us that Adam, immediately upon his creation, and before the appearance of Eve, was placed in the Garden of Eden. The problem of the geographical position of Eden has greatly vexed the spirits of the learned in such matters, but there is one point respecting which, so far as I know, no commentator has ever raised a doubt. This is, that of the four rivers which are said to run out of it, Euphrates and Hiddekel are identical with the rivers now known by the names of Euphrates and Tigris. But the whole country in which these mighty rivers take their origin, and through which they run, is composed of rocks which are either of the same age as the chalk, or of later date. So that the chalk must not only have been formed, but after its formation the time required for the deposit of these later rocks and for their upheaval into dry land must have elapsed, before the smallest brook which feeds the swift stream of "the great river, the river of Babylon," began to flow. Thus evidence which cannot be rebutted, and which need not be strengthened, though if time permitted I might indefinitely increase its quantity, compels you to believe that the earth, from the time of the chalk to the present day, has been the theatre of a series of changes as vast in their amount as they were slow in their progress. The area on which we stand has been first sea and then land for at least four alternations, and has remained in each of these conditions for a period of great length. Nor have these wonderful metamorphoses of sea into land, and of land into sea, been confined to one corner of England. During the chalk period, or "cretaceous epoch," not one of the present great physical features of the globe was in existence. Our great mountain ranges, Pyrenees, Alps, Himalayas, Andes, have all been upheaved since the chalk was deposited, and the cretaceous sea flowed over the sites of Sinai and Ararat. All this is certain, because rocks of cretaceous or still later date have shared in the elevatory movements which gave rise to these mountain chains, and may be found perched up, in some cases, many thousand feet high upon their flanks. And evidence of equal cogency demonstrates that, though in Norfolk the forest-bed rests directly upon the chalk, yet it does so, not because the period at which the forest grew immediately followed that at which the chalk was formed, And it is by the population of the chalk but because an immense lapse of time, rep-sea that the ancient and the modern inhabresented elsewhere by thousands of feet of itants of the world are most completely conrock, is not indicated at Cromer. nected. The groups which are dying out flourish side by side with the groups which are now the dominant forms of life. I must ask you to believe that there is no less conclusive proof that a still more prolonged succession of similar changes occurred before the chalk was deposited. Nor have we any reason to think that the first term in the series of these changes is known. The oldest sea-beds preserved to us are sands, and mud, and pebbles, the wear and tear of rocks which were formed in still older oceans. But, great as is the magnitude of these physical changes of the world, they have been accompanied by a no less striking series of modifications in its living inhabitants. Thus the chalk contains remains of those strange flying and swimming reptiles, the pterodactyl, the ichthyosaurus, and the plesiosaurus, which are found in no later deposits, but abounded in preceding ages. The chambered shells called ammonites and belemnites, which are so characteristic of the period preceding the cretaceous, in like manner die. with it. But amongst these fading remainders of a previous state of things are some very modern forms of life, looking like Yankee pedlars among a tribe of Red Indians. All the great classes of animals, beasts Crocodiles of modern type appear; bony of the field, fowls of the air, creeping things, fishes, many of them very similar to existand things which dwell in the waters, flour- ing species, almost supplant the forms of ished upon the globe long ages before the fish which predominate in more ancient seas; chalk was deposited. Very few however, and many kinds of living shell-fish first beif any, of these ancient forms of animal life came known to us in the chalk. The vegewere identical with those which now live. tation acquires a modern aspect. A few Certainly, not one of the higher animals living animals are not even distinguishable was of the same species as any of those as species from those which existed at that now in existence. The beasts of the field remote epoch. The Globigerina of the in the days before the chalk were not our present day, for example, is not different beasts of the field, nor the fowls of the air specifically from that of the chalk; and the such as those which the eye of man has same may be said of many other Foramiseen flying, unless his antiquity dates in-niferæ. I think it probable that critical and finitely further back than we at present surmise. If we could be carried back into those times, we should be as one suddenly set down in Australia before it was colonized. We should see mammals, birds, reptiles, fishes, insects, snails, and the like, clearly recognisable as such, and yet not one of them would be just the same as those with which we are familiar, and many would be extremely different. unprejudiced examination will show that more than one species of much higher animals have had a similar longevity, but the only example which I can at present give confidently is the snake's-head lamp-shell (Terebratulina caput serpentis), which lives in our English seas and abounded (as Terebratulina striata of authors) in the chalk. The longest line of human ancestry must hide its diminished head before the pedigree From that time to the present, the popu- of this insignificant shell-fish. We Englishlation of the world has undergone slow and men are proud to have an ancestor who was gradual but incessant changes. There has present at the Battle of Hastings. The anbeen no grand catastrophe. -no destroyer cestors of Terebratulina caput serpentis may has swept away the forms of life of one have been present at a battle of Ichthyosauperiod, and replaced them by a totally new rice in that part of the sea which, when the creation; but one species has vanished and chalk was forming, flowed over the site of another has taken its place; creatures of Hastings. While all around has changed, one type of structure have diminished, those this Terebratulina has peacefully propagated of another have increased, as time has its species from generation to generation, passed on. And thus, while the differences and stands to this day, as a living testimony between the living creatures of the time to the continuity of the present with the before the chalk and those of the present past history of the globe. day appear startling, if placed side by side, we are led from one to the other by the most gradual progress, if we follow the course of Nature through the whole series of those relics of her operations which she has left behind. Up to this moment I have stated, so far as I know, nothing but well-authenticated facts, and the immediate conclusions which they force upon the mind. But the mind is so constituted that it does not willingly rest in facts and immedi- | lar species may have lived on from epoch ate causes, but seeks always after a knowl- to.epoch.) Thus each epoch has had its edge of the remoter links in the chain of peculiar crocodiles, though all since the causation. I am not certain that any one can give you a satisfactory answer to that question. Assuredly I cannot. All that can be said for certain is, that such movements are part of the ordinary course of nature, inasmuch as they are going on at the present time. Direct proof may be given that some parts of the land of the northern hemisphere are at this moment insensibly rising and others insensibly sinking; and there is indirect but perfectly satisfactory proof, that an enormous area now covered by the Pacific has been deepened thousands of feet since the present inhabitants of that sea came into existence. Thus there is not a shadow of a reason for believing that the physical changes of the globe in past times have been effected by other than natural causes. chalk have belonged to the modern type, and differ simply in their proportions, and in such structural particulars as are discernible only to trained eyes. How is the existence of this long succession of different species of crocodile to be accounted for? Only two suppositions seem to be open to us - Either each species of crocodile has been specially created, or it has arisen out of some pre-existing form by the operation of natural causes. Choose your hypothesis; I have chosen mine. I can find no warranty for believing in the distinct creation of a score of successive species of crocodiles in the course of countless ages of time. Science gives no countenance to such a wild fancy; nor can even the perverse ingenuity of a commentator pretend to discover this sense in the simple words in which the writer of Genesis records the proceedings of the fifth and sixth days of the Creation. On the other hand, I see no good reason for doubting the necessary alternative, that all these varied species have been evolved from pre-existing crocodilian forms by the operation of causes as completely a part of the common order of nature as those which have effected the changes of the inorganic world. Is there any more reason for believing that Few will venture to affirm that the reasonthe concomitant modifications in the forms of ing which applies to crocodiles loses its the living inhabitants of the globe have been force among other animals, or among plants. brought about in other ways? If one series of species has come into exBefore attempting to answer this ques-istence by the operation of natural causes, tion, let us try to form a distinct mental it seems folly to deny that all may have picture of what has happened in some spe- arisen in the same way. cial case. The crocodiles are animals which, as a A small beginning has led us to a great group, have a very vast antiquity. They ending. If I were to put the bit of chalk abounded ages before the chalk was depos- with which we started into the hot but obited; they throng the rivers in warm cli- scure flame of burning hydrogen, it would mates at the present day. There is a dif- presently shine like the sun. It seems to ference in the form of the joints of the back- me that this physical metamorphosis is no bone, and in some minor particulars, between false image of what has been the result of the crocodile of the present epoch, and those our subjecting it to a jet of fervent though which lived before the chalk; but, in the nowise brilliant thought to-night. It has cretaceous epoch, as I have already men- become luminous, and its clear rays, penetioned, the crocodiles had assumed the mod-trating the abyss of the remote past, have ern type of structure. Notwithstanding brought within our ken some stages of the this, the crocodiles of the chalk are not evolution of the earth. And in the shifting identically the same as those which lived in" without haste, but without rest" of the the times called "older tertiary," which succeeded the cretaceous epoch; and the crocodiles of the older tertiaries are not identical with those of the newer tertiaries, nor are these identical with existing forms. (I leave open the question whether particu land and sea, as in the endless variation of the forms assumed by living beings, we have observed nothing but the natural product of the forces originally possessed by the substance of the universe. From Fraser's Magazine. ON THE FAILURE OF NATURAL SELEC -- The most perfect specimens of each race and This explains not only those extraordinary changes in the form and habits of the same animals which, when aided and aggravated by man's requirements and careful ticated races, but also those purely natural management, strike us so forcibly in domes TION IN THE CASE OF MAN. EVERY one now is familiar with the Darwinian theory of the origin of species, at least in its main principles and outlines: and nearly all men qualified to form an opinion are convinced of its substantial truth. That theory explains how races of animals vary as ages roll on, so as to adapt themselves to the changing external conditions which those ages bring about. At every given moment, in every given spot on the earth's surface, a struggle for existence' is going on among all the forms of organic life, animal and vegetable, then and there alive; a struggle in which, as there is not room for all, the weaker and less adapted succumb, while the stronger and better adapted survive and multiply. As surrounding circumstances, climatic or geological, vary and are modified, corresponding variations (such as are always incidentally appearing among the off- though far slower modifications which geooff-logical spring of all creatures) in the inhabitants logical researches have brought to our of each district crop up, increase, spread, knowledge. Mr. Wallace, in the admirable and become permanent. The creatures that model of succinct statement and lucid reapaper quoted below which is a perfect are most in harmony with surrounding circumstances have a manifest daily and hourly up the heat of the system. Our supposed perfect advantage over those which are less in har- animal is no longer in harmony with its universe; mony: live when they die; flourish when it is in danger of dying of cold or of starvation. But the animal varies in its offspring. Some of these are they fade; endure through what kills others; swifter than others- they still manage to catch can find food, catch prey, escape enemies, food enough; some are hardier and more thickly when their feebler, slower, blinder breth-furred-they manage in the cold nights to keep warm enough; the slow, the weak, and the thinly ren are starved and slain.* Thus the clad soon die off. Again and again, in each succeeding generation, the same thing takes place. By this natural process, which is so inevitable that it cannot be conceived not to act, those best adapted to live, live; those least adapted, die. It is sometimes said that we have no direct evidence of the action of this selecting power in nature. But it seems to me we have better evidence than even direct observation would be, because it is more universal, viz. the evidence of necessity. It must be so; for, as all wild animals increase in a geometrical ratio, while their actual numbers remain on the average stationary, it follows that as many die annually as are born. If, therefore, we deny natural se lection, it can only be by asserting that in such a case as I have supposed the strong, the healthy, the swift, the well clad, the well organised animals in every respect, have no advantage over, — do not on the average live longer than, the weak, the unhealthy, the slow, the ill clad, and the imperfectly organised individuals; and this no sane man has yet been found hardy enough to assert. But this is not all; for the offspring on the average resemble their parents, and the selected portion of each succeeding generation will therefore be stronger, swifter, and more thickly furred than the last; and if this process goes on for thousands of generations, our animal will have again become thoroughly in harmony with the new conditions in which he is placed. But he will now be a different creature. He will be not only swifter and stronger, and more furry; he will also probably have changed in colour, in form, perhaps have acquired a longer tail, or differently shaped ears; for it is an ascertained fact, that when one part of an animal is modified, some other parts almost always change as it were in sympathy with it. Wallace On the Origin of Human Races.' Journal of the Anthropological Society, No. 5. *The grand feature in the multiplication of organic life is that of close general resemblance, combined with more or less individual variation. The child resembles its parents or ancestors more or less closely in all its peculiarities, deformities, or beauties; it resembles them in general more than it does any other individuals; yet children of the same parents are not all alike, and it often happens that they differ very considerably from their parents and from each other. This is equally true of man, of all animals, and of all plants. Moreover, it is found that individuals do not differ from their parents in certain particulars only, while in all others they are exact duplicates of them. They differ from them and from each other in every particular: in form, in size, in colour, in the structure of internal as well as of external organs; in those subtle peculiarities which produce differences of constitution, as well as in those stil more subtle ones which lead to modifications of mind and character. In other words, in every possible way, in every organ and in every function, individuals of the same stock vary. Now, health, strength, and long life are the results of a harmony between the individual and the universe that surrounds it. Let us suppose that at any given moment this harmony is perfect. A certain animal is exactly fitted to secure its prey, to escape from its enemies, to resist the inclemencies of the seasons, and to rear a numerous and healthy offspring. But a change now takes place. A series of cold winters, for instance, come on, making food scarce, and bringing an immigration of some other animals to compete with the former inhabitants of the district. The new immigrant is swift of foot and surpasses its rivals in the pursuit of game; the winter nights are colder, and require a thicker fur as a protection, and more nourishing food to keep |