enjoyment out of life.

Luckily for the world, if not for its heroes, men's characters cannot be fixed by such calculations; and a certain number of perverse people are even glad to possess vehement emotions and restless intellects, however conscious that the fiery soul will wear out the pigmy body. We try to persuade ourselves that they are not only choosing the noblest part, but acting most wisely for their own interests. It may be so; for the problem is a complex one. But it has not yet been proved that a man can always make the

best of both worlds, and that the sacrifices imposed by virtue are always repaid in this life. Certainly it seems doubtful, when we have studied the self-written records of remarkable men, whether experience will confirm that pleasant record; whether it is not more probable that for simple employment it is not best to have one's nature pitched in a key below the highest. Most of us would make a very fair compromise if we should abandon our loftier claims on condition of being no worse than Gibbon.-Cornhill Magazine.

"It is not too much to say that every spot which is now dry land has been sea at some former period, and every part of the space now covered by the deepest ocean has been land." This sentence occurs in the latest edition of Lyell's "Principles of Geology," still perhaps the most authoritative text-book on the subject, and the view it expresses has been generally received as an article of faith by geologists until within a few years, or even months ago.

Lately a change of view has taken place, and now many distinguished men hold the completely opposite opinion that oceans have been permanent from the remotest times, and that continents are, and have ever been, fixed lands, subjected to ceaseless modifications of form. Among the most conspicuous partisans of the new theory are Sir Wyville Thomson, Prof. Geikie, and Mr. Wallace; and the latter especially seems to have collected together and presented in his fascinating book, "Island Life," every kind of evidence that tends to support it. Nothing appears to have escaped him, yet the whole when summed up must seem to every geologist to fall far short of proof. Still, although the evidence upon which the theory is based is as yet wholly insufficient, it by no means follows that the theory itself is improbable.

The chief evidence upon which the Permanence of Continents at present rests, is purely geological. It is argued

that the whole of the sedimentary rocks are littoral deposits, or those of inland seas; and if this can be maintained, the theory would, almost as a matter of course, be accepted. Mr. Wallace, therefore, endeavors by every mcans to prove it.

Chief among deposits hitherto supposed to be oceanic, is the chalk; and to the discussion of this formation, accordingly, almost a whole chapter is devoted. Mr. Wallace expresses the belief that, far from the chalk sea representing a wide ocean with a few scattered islands comparable to some parts of the Pacific, it formed as truly a portion of the great northern continent as it does now."

The evidence which he has to set aside, in favor of the chalk being a truly oceanic deposit, is extremely weighty, however, and by no means easily disposed of. Its vast extentstretching from Sweden to Bordeaux, and from Ireland to China-and its freedom everywhere from impurities derived from the degradation of land, are greatly in favor of its oceanic origin. The areas that are known to have been denuded, and the enormous deposits of flint-shingles which characterize the Eocenes from their base upward to the most recent gravels, show how colossal this denudation has been.

The chalk that has escaped seems but the fragment of a mass which once passed under the Atlantic, for even the

which it has penetrated the minutest pores of Echinoderms before destroying the shell; and it seems probable from the way in which it has replaced carbonate of lime,* that it had not parted with its organic acids. That it did not assume the solid state until at least after the partial consolidation of the chalk is obvious, through the filling in of fissures at right angels to the bedding, which could not have existed when it formed the surface sediment of the ocean bottom. In comparing the white chalk analysis with that of the ooze, therefore, we must bear in mind that, as already pointed out by Mr. Sorby, Mr. Sollas, and Dr. Wallich, a portion of flint must be added equal to that which has been separated away. In a similar manner, iron has been removed and segregated together, to be crystallized principally into globular balls with a radiating structure. The shells composed of carbonate of lime, such as those of Gastropods, Cephalopods, and Dimyaria, seem also to have been dissolved away, perhaps by the rainwater which falls upon the chalk, saturates it, and passes through it by capillary action unceasingly. Another evidence of change is shown in the crystalline condition of shells composed of phosphate of lime, such as the Aviculidæ, the Branchiopoda, the Echinodermata, etc.

It is surprising to find that no allusion whatever is made to this range of facts by Mr. Wallace; and those of his readers who are unacquainted with

*All the carbonate-of-lime shells are replaced in the Blackdown deposits by silica.

It assumes very beautiful forms in the grey chalk, and has occasionally completely

replaced sponges. The iron is frequently

ochreous in the white chalk.

Gastropods are found as casts in the grey chalk, slightly coated with iron, and occasionally traces are met in the lower white chalk in the same condition. Higher that this even the most indistinct outlines of the larger forms, such as Pleurotomaria, are rare. I have seen but one trace of shell on any spiral Gastropod, and this on a fragment of Funis from the white chalk near Norwich. Small thin fragments adhered to the cast, and the circumstance is remarkable, as Funis almost alone of the Gastropods preserves its shell in the Cambridge greensand. The shells of Cephalopods seem to possess a slightly greater resisting power, and their casts are, as a rule, more distinct.

them, are left unaware that chalk has undergone such great changes in its composition since it was the bed of the sea as to deprive the unqualified statement that the analyses of chalk and Globigerina ooze " do not even approximately agree," of any scientific value.

These facts further tend to show, as indeed is obvious from a comparison of the faunas, that the similarity in the analysis of the Oahu chalk and the white chalk, upon which so much stress is laid, is purely superficial.* In spite of the fact that this chalk consists simply of comminuted corals and shells of the reef," and is, when examined microscopically, "found to be destitute of the minute organisms abounding in the chalk of England, "Mr. Wallace states that in several growing reefs a similar formation of modern chalk, undistinguishable from the ancient, has been observed.

Mr. Wallace thus assumes that the chalk is derived from excessively fine mud produced by the decomposition and denudation of coral reefs; but this view appears to me to be untenable. Mr. Murray expressly states that no Globigerina were found in any of the inclosed seas of the Pacific which possess this chalky bottom; and to account for Globigerina in the chalk it has to be supposed that the chalk sea was open to the gulf stream, i.e. the Atlantic. Further, to provide the necessary conditions we are obliged to suppose this vast sea to have been bordered with islands and coral reefs, and that no large rivers flowed into it; and yet absolutely no traces of these coral reefs remain, while an inland sea could hardly have existed in proximity to a great permanent continent without some rivers draining into it. A curious piece of reasoning is that in the Maestricht and Faxoe chalks

chalk." If these local and far newer deposits are seen to be highly coralline and the chalk is not seen to be so, we have rather a clear indication that they were not deposited under the same conditions. The presence of Mosasaurus in the Maestricht beds, and the far newer aspect of its fauna, show that it must have belonged to an altogether different period, probably the one represented in America by a great so-called cretaceous series containing a mixture of cretaceous and tertiary mollusca, dicotyledonous plants, and Mosasaurus. From every point of view, in fact, the inference that the vast cretaceous deposits are analogous to small local deposits of coral mud in the Pacific does not appear to be the true one.

With regard to the probable depth of the ocean which deposited the chalk, the evidence brought together by Mr. Wallace is less unsatisfactory. Mr. J. Murray, for instance, sees the greatest resemblance to it in mud from depths of less than 1000 fathoms; and Dr. Gwyn Jeffreys finds that all the Mollusca of the chalk are comparatively shallow-water forms. We must bear in mind, however, that the characteristically deep-sea families and genera, such as Bulla and the Solenoconchia, Leda, Neara and Verticordia, would have long since been dissolved away if present; while great and highly characteristic cretaceous genera, such as Inoceramus and Hippurites, are wholly extinct and nothing therefore can be safely predicated concerning their habits.

In the grey chalk near Folkestone dark impressions of nearly all the deepsea mollusca enumerated above are abundant; and the Gault and a part of the Lower Greensand are full of their shells in perfect preservation. Their absence in England at least, from the chalk, seems very clearly due rather to subsequent destruction than to their never having been present. Of the chalk genera that are preserved, Pecten, Amussium, Lima, Spondylus, Anomia, and the Brachiopoda are represented by Dr. Gwyn Jeffreys as having been dredged at from 1450 to 1750 fathoms and upward. As for the abundance of Ammonites showing, as Dr. S. P. Woodward once supposed, the water to have been as shallow as thirty fathoms, Mr.

Wallace himself would be the first to repudiate such mere supposition, were it urged against the theory he seeks to establish. Were Nautilus and Spirula shallow-water forms they would long since have been captured abundantly. The still existing shells of the chalk itself are so few that little weight can be attached to them as an indication of depth, but in the lower cretaceous deposits mollusca abound, as already stated, and in perfect preservation; and their facies, taken with the complete absence of shallow-water forms, implies, Dr. Gwyn Jeffreys believes, a depth of sea in the Gault period of somewhere about 1000 fathoms. Mr. Sorby, from quite other considerations, believed the Gault to be an altered red clay, similar in all essential respects to the red clay now forming at the ocean-bottom. There seems thus to be abundant evidence, indorsed by our greatest authorities, that at least some of the cretaceous deposits were deep-sea, while there is a total absence in them of anything necessarily indicating the proximity of land.* With regard to the chalk itself, however, the facts are still somewhat contradictory, for it far overlaps the Gault and grey chalk in Devonshire, and rests upon greensand; yet although it thins out to the west it remains a perfectly pure rock, without any apparent evidence of the upper part of the formation having gradually shallowed as the seabed became upheaved.

The immensity of the gap, seldom adequately realized, between the true cretaceous and the next overlying beds, implies an interval sufficient to have permitted the grandest changes in the distribution of land and water, and the gulf of the Atlantic, which stretched over the greater part of Europe, to become elevated; and, after enormous denudation, to be converted into land.

But even altogether apart from what is to be learned from the cretaceous rocks, it is not apparent that continents have been uninterruptedly permanent. Australia and Asia, Africa and Mada

* No American or European so-called cretaceous land-flora can be proved to be as old as our white chalk. The few vegetable remains found in marine cretaceous rocks are not incompatible with the deposit having taken place at a distance from shore.