in all the countless ages which have rolled away since the branches of Zamia were blown into the lagoon of Stonesfield, the amount of organic change has been small in each group of plants and animals ; that a similar amount of change affected the unlike inhabitants of land and sea; that Mollusca and Sharks, and Turtles and Crocodiles, have all been modified by differences of a small description in passing from Oolitic to modern times, while not only hosts of Ammonites and Belemnites have perished in the experiment, but many new forms, as Oliva, Mitra, Triton, Struthiolaria, unknown in the earlier period, have come into view in the latter! But let it be adopted. What follows? These small differences then, accomplished in all that prodigious range of elapsed time, under all that variety of physical changes and removals, these are all the mutations which have been possible under the constant tendency of hereditary descent to perpetuate similar forms with modification.

One of these genera, that of Trigonia, is known to be in the fossil state rich in species; supposing them to have all come from one original typical form, the differences which they shew in strata of the same system, deposited within the same grand period, and under much similarity of conditions, argues a facility in giving variations; let this operation be supposed

to be continued in the interval between the epoch of Stonesfield and that of Australia, and the effects summed by natural selection, the result is the modern Trigonia, scarcely differing more in appearance from the fossil species than they differ one from another.

But if not so derived, by continual descent, but sprung from separate contemporaneous branches of one stem of life, arriving at a given standard of excellence at such enormously different epochs, how should it happen that Plants and Quadrupeds on land, Sharks and Mollusks in the sea, should in each of these two cases pass with equal advance along the streams of change, moving in one case so fast, in the other so slow? But if the branches sprang at different times and led to these similar results, would this double origin in time, for several similar forms, in similar associations, fit with the hypothesis of continual development?

THEORIES AND OPINIONS.

FORMED STONES.

THREE centuries have glided by since Bernard Palissy, the philosophic potter of Xaintonge, revived the ancient opinion of Herodotus' and Pythagoras3, and wrote the simple words,

'Je t'ay monstré plusieurs coquilles reduites en pierre.'

France may well be proud of him, for he was among the first who ever uttered in modern Europe sensible remarks on the subject of Palæontology, and they fell on incredulous ears.

Two centuries only remove us from Agostino Scilla, the worthy Italian painter, who strove to dissipate false speculations regarding petrified marine exuviæ, by excellent drawings of recent and fossil teeth, Echinida and shells, from the Tertiary Strata of Messina and Malta. What these false speculations were, is too well known to the readers of our earliest English authors, Plot, Llwydd, Lister, Ray, and Wood2 Ovid, Metam.

1 Euterpe, 12.

3 The first of Palissy's Essays is dated 1557; the complete work 1580; Gessner's work, De omni rerum fossilium genere, &c., was printed at Zurich in 1565.

* La vana speculazione disingannata. Earliest Edition, 1670.

ward, who consumed the latter part of the seventeenth century in wrangling about 'formed stones,' 'plastic forces,' and 'lusus naturæ.'

The learned Dr Robert Plot, the first Keeper of the Ashmolean Museum in Oxford, in that valuable Natural History of Oxfordshire (1677), which was the model for many goodly volumes in other counties of England, after carefully describing many Ophiomorphites, Ostracites, Belemnites, and Cockles lying in their stony sepulchres, is brought to consider the great question then so much controverted in the world.

'Whether the stones we find in the form of shellfish, be lapides sui generis, naturally produced by some extraordinary plastic virtue latent in the earth or quarries where they are to be found? Or whether they rather owe their form and figuration to the shells of the fishes they represent, brought to the places where they are now found by a deluge, earthquake, or some other such means, and there being filled with mud, clay, and petrifying juices, have in tract of time been turned into stones, as we now find them, still retaining the same shape on the whole, with the same lineations, sutures, eminences, cavities, orifices, points, that they had whilst they were shells.

'In the handling whereof' (he tells us), 'though I intend not any peremptory decision, but a friendly

debate; yet having according to the wishes and advice of those eminent virtuosi, Mr Hook and Mr Ray, made some considerable collections of these kind of things, and observed many particulars and circumstances concerning them; upon mature consideration, I must confess I am inclined rather to the opinion of Mr Lister, that they are lapides sui generis; than to theirs, that they are thus formed in an animal mould. The latter opinion appearing at present to be pressed with far more and more insuperable difficulties than the former. For they that hold these stones were thus formed in the shells of fishes, must suppose either with Steno, that they were brought hither by the Deluge in the days of Noah; or by some other more particular and perhaps national flood, such as the Ogygean or Deucalionian in Greece, than either of which there is nothing more improbable.'

His argument against the Noachian origin of the figured stones is very complete; first, that it was not universal, but confined to the continent of Asia; and next, that if it were universal it could not have produced the effects which require to be explained, whether it were occasioned by rain, or the breaking up of the sea, and whether it were violent or gradual.

R. L.

N