lent and partial, broken up and shivered; whereas the granitic strata existed in the state of the same glass-panes brought to a bright red heat, and capable, from their extreme flexibility, of being bent and twisted in any direction. We find, too, that there occur occasional patches in which the lines of the stratification have been altogether obliterated. We can trace the strata with much distinctness on every side of these; but there is a gradual obscuration of the lines, and we see what was a granitic gneiss in one square yard of rock existing as a compact homogeneous mass in the next. The effect is exactly that which would be produced in the heated panes of my illustration, were the heat kept up until portions of them began to run; and the circumstance serves to throw light on some of the other phenomena of the gneiss. The stone, in its average specimens, is a ternary, consisting of red feldspar, white quartz, and a dingy-coloured mica; but no one, notwithstanding, could mistake it for a true granite. It has its granite veins, however; and these veins, truly such in some cases, are, in not a few others, mere strata of the gneiss, which have evidently been formed into granite where they lie. There are no marks of injection,-no accompanying disturbance: all their conditions, with the exception of their being true granites, are exactly those of the layers which repose over and under them. Now the homogeneous patches serve, as I have said, to throw light on the secret of the formation of these. In one important respect the granitic rocks differ widely among themselves. Some of them contain potass and soda in such large proportions, and have such a tendency to disintegrate, in consequence, that they furnish much less durable materials for building than the better sandstones; while others, of an almost indestructible quality, are devoid of these salts altogether. Potass and soda form powerful fluxes; and it seems at least natural to infer that, should wide tracts of granitic rock be exposed to an intense but equable heat, the portions of the mass in which the fluxes exist in large proportions must pass into a much higher state of fluidity than the portions in which they are less abundant, or which are altogether devoid of them. Single strata and detached masses might thus come to be in the state of extremest fusion of which their substance was capable, and all their particles, disengaged, might be entering freely into the combinations peculiar to the plutonic rocks, when all around them continued to bear the semi-chemical, semi-mechanical characteristics of the metamorphic ones. Hence it is possibly the origin of some of those granite veins, open above, and terminating below in wedge-like points, which have so puzzled the Huttonians of a former age, and which have been so triumphantly referred to by their opponents as evidences that the granite had been precipitated by some aqueous solution. SEPTARIA OR CEMENT-STONES OF THE LIAS. OBSERVE these nodular masses of pale blue limestone, that seem as if they had cracked in some drying process, and had afterwards the cracks carefully filled up with a lightcoloured cement. The flaws are occupied by a rich calcareous spar; and in the centre of each mass we find, in most instances, a large ill-preserved Ammonite, which has also its spar-filled cracks and fissures, as if it, too, had been burst asunder by the process which had rent the surrounding matrix. These nodular masses are the characteristic septaria or cement-stones of the Lias, so much used in England for making a hard, enduring mortar, that has the quality of setting under water. Their bluish-coloured portions are so largely charged with the argillaceous matter of the bed in which they occur, and contain, besides, so considerable a mixture of iron, that, refusing to slake like common lime, they have to be crushed, after calcination, by mechanical means ; while the fossil in the centre, and the semi-transparent spar of the cracks, are composed of matter purely calcareous. And from this peculiar mixture this cement seems to derive those setting qualities which render it of such value. AMMONITES OF THE NORTHERN LIAS. THE Ammonites of the upper beds of the Lias approach more to the type of the Ammonite communis, being comparatively flat when viewed sectionally, and having the whorls broadly visible, as in the Ionic volute; while the Ammonites of the lower beds approach in type to the Ammonite heterophyllus, each succeeding whorl covering so largely the whorl immediately under it, that the spiral line seems restricted to a minute hollow in the centre, scarce equal in extent, in some specimens, to the twentieth part of the entire area.. In other words, the Ammonites of the Upper Lias in this deposit represent, as a group, the true ammonite type; while in the Lower Lias they approach more nearly as a group to the type of the nautilus. And not only are they massier in form, but also absolutely larger in size. I have found Ammonites in the more ponderous septaria, that fully doubled in bulk any I ever saw in the upper shales. We occasionally find nodules that, having formed in the outer rings of these larger shells, somewhat resemble the rims of wheels,-in some cases, wheels of not very diminu tive size. BELEMNITES OF THE NORTHERN LIAS. WE find the Belemnites of the lower deposit, like its Ammonites, of a bulkier form than those of the upper beds. The Belemnites abbreviatus and elongatus, both large, massy species, especially the former, are of common occurrence ; while those most abundant in the upper beds are the Belemnites longissimus and penicillatus, both exceedingly slim species. It is worthy of remark, that Sir R. Murchison, in his list of fossils peculiar to the Lias as developed in the midland counties of England, specifies the Belemnites penicillatus as characteristic of its upper, and the Belemnites abbreviatus and elongatus of its lower division. CUTTLE-FISH. Is the reader acquainted with at once the largest and most curious of British Mollusca,-the cuttle-fish,—a creature which stands confessedly at the head of the great natural division to which it belongs? Independently of its intrinsic interest to the naturalist, it bears for the commentator and the man of letters an interest of an extrinsic and reflected kind. No other mollusc occupies so prominent a place in our literature. It is furnished with an ink-bag, from which, when pursued by an enemy, it ejects a dingy carbonaceous fluid, that darkens the water for yards around, and then escapes in the cloud,-like some Homeric hero worsted by his antagonist, but favoured by the gods, or some body of military retreating unseen from a lost field, under the cover of a smoking shot. And there has scarce arisen a controversy since the days of Cicero, in which the cuttle-fish, with its ink-bag, has not furnished some one of the controversialists with an illustration. It has attained to some celebrity, too, on another and altogether different account. That enormous monster, the kraken of Norway, of which our earlier geographers tell such surprising stories, was held to belong to this curious family. And though the monster has disappeared from the treatises of our naturalists for a full half-century, and from the pages of even our more credulous voyagers for at least a century more, it maintained its place as a real existence long enough to be assigned a permanent niche in our literature. It has been described as raising its vast arms out of the water to the height of tall forest-trees, and as stretching its knobbed and warted bulk, roughened with shells, and darkened with seaweed, for roods and furlongs together,-resembling nothing less extensive than some range of rocky skerries on some dangerous coast, or some long chain of sand-banks forming the bar of some great river. It was introduced to the reading world with much circumstantiality of detail, by an old Norwegian bishop (Eric Pontoppidan), as an animal the largest in creation, whose body rises above the surface of the water like a mountain, and its arms like the masts of ships.' And one of the French continuators of Buffon,— Denys Montfort, regarding it as at least a possible existence, has given, in his history of Mollusca, a print of a colossal cuttle-fish hanging at the gunwale of a ship, and twisting its immense arms about the masts and rigging,—a feat which the cuttle-fish of the Indian seas is said sometimes to accomplish, if not with a ship, at least with a canoe. But nowhere does the kraken of Norway look half so imposing or half so poetical as in Milton. In palpable reference to the old bishop's 'largest animal in creation,' we find the poet describing, in one of his finest similes,— ' that sea beast, Moors by his side under the lee, while night The existing cuttle-fish of our seas, though vastly less T |