edentula; and bithinia ventricosa. Those which I found in other parts of the Towans, at various depths, are helix aspersa, nemoralis, hortensis virgata, and ericetorum; bulimus acutus; zua lubrica; and pupa marginata; in all, fourteen species, of which the most abundant, as well beneath as on the present surface, were the bulimus acutus, helix virgata, and helix ericetorum.

Mr R. Q. Couch, author of the Cornish Fauna, who kindly furnished me with the names of these shells, makes the following interesting remarks in his letter to me on the occasion. "Of the Helices all are common in the locality except the helix pulchella. This last I have found near Falmouth, at Pendennis; near Penzance, at Trereife; and near the Land's-end. It is, however, rare in this county. The quantity found on the Towans within so small a space is very remarkable, and should further research shew that they are of frequent occurrence in other parts of the Towans, we must come to the conclusion that they were once abundant in Cornwall, but are now gradually becoming extinct in this locality. The pupa marginata and bithinia ventricosa are very rare: I have found a few dead specimens near Hayle, and at Whitesand Bay, which might have come from the sand-hills, but I have not yet found them alive in Cornwall. It would be very desirable to examine the Towans at different depths, to ascertain the changes which the Fauna of our county has been undergoing during the last one or two thousand years."

*

The observations now made on the origin of the sand-hills of St Ives, are equally applicable to those of Whitesand Bay, near the Land's-end, and to the sand-banks of Mount's Bay, except that the last are principally granitic. I have examined the sand-bank between Penzance and Marazion, especially the highest part of it, near Marazion Bridge, and have found, throughout a depth of about 10 feet from the surface, a great number of land-shells (helix virgata and bulimus acutus) in perfect preservation, and in similar circumstances to those

* Besides the helix virgata and bulimus acutus, with which the sections of the sands of Whitesand Bay are thickly studded, I found there likewise a specimen of the clausilia bidentata.

already described; so that (like the sand-hills of St Ives and Whitesand bays) these sand-banks have apparently arisen from successive deposits which did not cover the growing turf, except occasionally, when, being more copious than usual, they have completely buried it, although not so deeply as to prevent its speedy reappearance above the sand.

To this process of accumulation by the agency of the winds, one very remarkable exception remains to be noticed. It occurs in the bank near Marazion Bridge, where, in one instance, a complete covering of the herbage appears to have proceeded directly from the sea-from the waves of an earthquake,* or some extraordinary high tide coinciding with a furious south wind. For in the section of this bank, a layer, an inch or two thick, of small rounded pebbles, may be seen 3 feet below the surface, and more than 15 feet above the level of high water; whilst in the subjacent sand, deposited probably by the winds alone, numerous perfect land shells are imbedded throughout a depth of 4 or 5 feet beneath the pebbles.

SCIENTIFIC INTELLIGENCE.

GEOLOGY AND MINERALOGY.

1. Example of apparent Drift-Furrows dependent on Structure. By C. B. Adams, State Geologist of Vermont, &c. (Communicated for this Journal.)-The attention of geologists having been lately called to the question, whether the grooves and striæ commonly attributed to drift agency, may not be due to structure, it may not be improper, in anticipation of the results of the survey of Vermont, to mention an example in which this is undoubtedly the case. Mr Macintosh, the author of the article which is alluded to, and which was read before the Geological Society of London, particularly suggests that such may be the origin of the examples the United States, described by President Hitchcock,-a suggestion, we will venture to add, which must have occasioned much surprise in those who are familiar with these effects of drift agency in the New England States, unless they also may have met with facts of the same nature with those which are the subject of this brief notice.

* See Trans. of the Royal Geological Society of Cornwall, 1843, p. 113. In this Journal, 2d Ser., vol. i., p. 277; and Sir R. I. Murchison's Geoogy of Russia and the Ural Mountains, vol. i., p. 566.

Not far from the geographical centre of Vermont, in the town of Randolph, on ascending a hill a mile east of the centre village, may be seen a ledge of argillo-mica-slate, in which the planes of lamination do not coincide with those of deposit. The former have a direction of north 35° east (true meridian), and a dip of 30° to the north, 55° west. The true strata have a direction of north and south, with a dip of 65° west; and although much less conspicuous than the cleavage planes, are distinguished, without much difficulty, by a slight difference of materials, in consequence of which they weather unequally, so as to form shallow grooves with a well-rounded excavation of 3 to 6 inches wide, and an inch deep. The coincidence of the direction of these grooves, with the ordinary cases of drift-furrows, and their obliquity to the planes of lamination, which are obvious to the passing traveller, who may not, without special examination, recognise the true stratification of the rock, as well as the well-rounded excavation of the grooves, due, no doubt, to the gradual transition in the characters of the strata, combine to present a case of extraordinary resemblance to genuine drift-furrows.

It is proper to add, that the examination of several hundred examples of rounded, smoothed, striated, and furrowed rocks, has brought to light only this case, in which structural grooves bear any resemblance to those which have resulted solely from an external mechanical force. The suggestion of Mr Macintosh is, therefore, plainly incapable of general or even common application, although cases may occur in which it is worthy of careful attention. Indeed, President Hitchcock has himself* most scrupulously distinguished the drift-furrows from those which are due to structure. Sir R. T. Murchison also remarks, that "the greater number of the deviously parallel scratches on the worn surface of the hard crystalline rocks of the north, are, in our opinion, clearly mechanical, and cannot be connected with structural condition."-American Journal of Science, Literature, and Arts, vol. iii., p. 433.

2. Food of the Mastodon.—(Proc. Bost. Nat. Hist. Soc.)-Professor Gray stated, that there had been recently placed in his hands specimens of earthy matter, filled with finely broken fragments of branches of trees, which were said to have been found occupying the place of the stomach in the skeleton of the mastodon exhumed on Schooley's Mountain, N. I., and lately exhibited in Boston. As similar observations are said to have been made in several instances, Professor Gray was induced to examine the substance brought to him. The wood evidently consisted of branchlets of one, two, and three years old, broken, quite uniformly, into bits of half an inch or so in length, with only now and then traces of the bark remaining on the wood. The wood was not at all fossilized, and was but slightly decayed. From the appearance of the branchlets examined, Professor

*Final Report on the Geology of Massachusetts, p. 385.

Gray inferred that they belonged to some coniferous tree or shrub, and probably to a kind of spruce fir, rather than to a true pine. This inference was borne out by the examination of thin slices of the wood by the microscope. The woody fibre was very beautifully and distinctly marked with the circular discs that are characteristic of all coniferous wood. The structure agreed quite perfectly with that in similar branchlets of the common hemlock spruce.-American Journal of Science, Literature, and Arts, New Series, vol. iii., No. 9, p. 436.

3. Large Plates of Mica.-The Vittim is remarkable for a mica mine, which is said to produce the largest and clearest sheets of the substance in the world, some of them being quite pure to the extent of two feet and a half square.Narrative of a Journey round the World, by Sir George Simpson, vol. ii., p. 334.

4. Lake Baikal.—Lake Baikal is about seven or eight hundred versts in length, and about seventy or eighty broad at its widest part. The waters are as clear as crystal, everywhere deep, and in many places unfathomable. Besides the numberless cascades that rush down its walls of mountains, it receives many rivers, more especially the Angara at its northern extremity, and the Selenga on its eastern side, towards the south; and its single outlet, in spite of the superior claims of the Selenga, on the double ground of position and magnitude, professes in its name to be a continuation of the remote and comparatively inconsiderable Angara. The two Angaras are sometimes distinguished from each other as Upper and Lower. The quantity of water which issues from the lake is believed to be vastly less than that which flows into it, the difference being, in all probability, too great to be explained by evaporation alone. In this view of the thing, a large portion, as a matter of course, must be absorbed, an operation which the volcanic origin of the huge hollow may be supposed likely to facilitate. In fact, the lake presents certain features which have induced individuals to infer that it has a subterranean communication with the ocean. It is the only body of fresh water in the world that possesses phocoe or seals; and when agitated, in the way already mentioned, by invisible curves, it throws up to its surface quantities of small fish, which are never seen at any other time. In illustration of the mysterious agencies of nature, which produces the same ends by contrary means, I subjoin two passages from Baron Wrangell's interesting work.

"These flat valleys are occasionally filled with water, by the overflowing of the rivers in spring, when they form lakes of various sizes, all very full of fish. The intense frosts of winter cause large clefts in the ground, by which the water drains off, sometimes in the course of a single year, sometimes in several.

"A curious phenomenon occurs in the lakes in the vicinity of the village of Alaseya. In the middle of winter, the water sometimes suddenly disappears without any side channels being visible.

In

such cases a loud noise is heard at the time the water disappears, and, when the bottom of the lake is laid bare, large clefts are visible, occasioned by the severity of the frost."Narrative of a Journey round the World, by Sir George Simpson, vol. ii., p. 381.

5. Chiolite, a new mineral from Miask; By Fr. v. Wörth.Chiolite is a massive mineral resembling cryolite. It occurs granular, with a shining lustre, and presenting a greyish, yellowish, or snow-white colour. The streak is snow-white. The hardness is bétween calc-spar and fluor-spar. Specific gravity of the masses, 2-6209; of the powder, 2.770. The structure of the massive pieces is imperfectly foliated, and the surface of foliation exhibits a lustre between greasy and vitreous. The specimen exhibited by M. Wörth indicated that it was associated with lithic mica, massive fluor-spar, and quartz. It melts easily in the flame of a candle, but at first decrepitates. Its transparency increases in water.

According to the chemical analysis of A. Chodner, it consists of aluminum 16-48, sodium 25.72, potassium 0.58, magnesium 0.76, yttrium 1.04, fluorine 56·00=100-38, giving the formula 2 Na Fl, and also in its higher specific gravity. The name chiolite is from the Greek word to snow. Verhandl. Min. Ges. zu St Petersburg, 1845-46.

6. Arsenic in Mineral Waters-Arsenic has been found by M. Valchner in various mineral waters at Viesbade in Germany, and this has been confirmed by M. Figuer. The last-mentioned chemist has ascertained that arsenic is in the state of arsenous acid, and that the proportion is nearly 0-045 grammes in 100 litres of the water. He detected no arsenic in the waters of Passy.-L'Institut, No. 670. 7. Nitrification.-M. Dumás states, that when a current of moist air containing ammonia is directed upon a solution of potash, the temperature being at 100° C., a quantity of nitrate of potash is formed through a change of the ammonia into nitric acid. He remarks that this experiment, which accords with the labours of M. Kuhlman on nitrification, was suggested to him by observations which he had recently made upon the conversion of sulphuretted hydrogen into sulphuric acid.—L'Institut, No. 674.

8. Phosphate of Lime in Organic Beings.-M. Dumas attributes the disaggregation of bones on exposure in the soil, and the removal of the phosphate of lime by water, to two causes, the one of feeble intensity, and acting rarely; the other of great force, and always in action. The first depends on the ammoniacal salt in waters, which salt enables them to dissolve phosphate of lime; this salt is everywhere present, but in so small a quantity as to have comparatively little influence. The second depends on carbonic acid, which appears to be the true solvent of phosphate of lime; for waters charged with carbonic acid, dissolve large quantities of it. Alkalies and ebullition separate the carbonic acid, and precipitate the salt. The action of this acid is so powerful, that shavings of ivory placed in a bottle of