mouth. It is in reality a bivalve of the Linnæan genus of mytilis and the species of crista galli; called by Lister, rastellum; by Rumphius, ostreum plicatum minus; by D'Argenville, auris porci, crista galli; and by those who make collections, cock's comb. Though I applied to several such in London, I never could meet with an entire specimen; nor could I ever find in books any engraving from a perfect one. In the superb museum at Leicester House, permission was given me to examine for this article; and though I was disappointed as to the fossil, I was highly gratified with the sight of several of the shells themselves, in high preservation. This bivalve is only known to inhabit the Indian ocean, where it fixes itself to a zoophyte, known by the name gorgonia.

Cornua ammonis are very common about this village. As we were cutting an inclining path up the Hanger, the labourers found them frequently on that steep, just under the soil, in the chalk, and of a considerable size. In the lane above Well-head, in the way to Emshot, they abound in the bank in a darkish sort of marl; and are usually very small and soft: but in Clay's Pond, a little farther on, at the end of the pit, where the soil is dug out for manure, I have occasionally observed them of large dimensions, perhaps fourteen or sixteen inches in diameter. But as these did not consist of firm stone, but were formed of a kind of terra lapidosa, or hardened clay, as soon as they were exposed to the rains and frost, they mouldered away. These seemed as if they were a very recent production. In the chalk-pit, at the northwest end of the Hanger, large nautili are sometimes observed.

In the very thickest strata of our freestone, and at considerable depths, well-diggers often find large scallops or pectines, having both shells deeply striated, and ridged and furrowed alternately. They are highly impregnated with, if not wholly composed of, the stone of the quarry.

IV.

As, in last letter, the freestone of this place has been only mentioned incidentally, I shall here become more particular.

This stone is in great request for hearth-stones, and the beds of ovens; and in lining of lime-kilns it turns to good account; for the workmen use sandy loam instead of mortar; the sand of which fluxes,* and runs, by the intense heat, and so cases over the whole face of the kiln with a strong vitrified coat like glass, that it is well preserved from injuries of weather, and endures thirty or forty years. When chiselled smooth, it makes elegant fronts for houses, equal in colour and grain to the Bath stone; and superior in one respect, that, when seasoned, it does not scale. Decent chimneypieces are worked from it of much closer and finer grain than Portland; and rooms are floored with it; but it proves rather too soft for this purpose. It is a freestone, cutting in all directions; yet has something of a grain parallel with the horizon, and therefore should not be surbedded, but laid in the

There may probably be also in the chalk itself that is burnt for lime a proportion of sand; for few chalks are so pure as to have none.

same position that it grows in the quarry.* On the ground abroad this fire-stone will not succeed for pavements, because, probably some degree of saltness prevailing within it, the rain tears the slabs to pieces. Though this stone is too hard to be acted on by vinegar; yet both the white part, and even the blue rag, ferment strongly in mineral acids. Though the white stone will not bear wet, yet in every quarry, at intervals, there are thin strata of blue rag, which resist rain and frost, and are excellent for pitching of stables, paths, and courts, and for building of dry walls against banks; a valuable species of fencing, much in use in this village, and for mending of roads. This rag is rugged and stubborn, and will not hew to a smooth face; but is very durable: yet, as these strata are shallow and lie deep, large quantities cannot be procured but at considerable expense. Among the blue rags turn up some blocks tinged with a stain of yellow or rust colour, which seem to be nearly as lasting as the blue; and every now and then balls of a friable substance, like rust of iron, called rust balls.

In Wolmer forest I see but one sort of stone, called by the workmen sand, or forest stone. This is generally of the colour of rusty iron, and might

To surbed stone is to set it edgewise, contrary to the posture it had in the quarry, says Dr Plot, Oxfordsh. p. 77. But surbedding does not succeed in our dry walls; neither do we use it so in ovens, though he says it is best for Teyn

ton stone.

+Firestone is full of salts, and has no sulphur: must be close-grained, and have no interstices. Nothing supports fire like salts; saltstone perishes exposed to wet and frost." Plot's Staff. p. 152.

B

their residence for such a series of years, that the oak was distinguished by the title of The Raven Tree. Many were the attempts of the neighbour ing youths to get at this eyry: the difficulty whetted their inclinations, and each was ambi tious of surmounting the arduous task. But when they arrived at the swelling, it jutted out so indi their way, that and was so far beyond their the most daring lads were awed, and acknowled ged the undertaking to be too hazardous. S ravens built on, nest upon nest, in perfec ty, till the fatal day arrived in which was to be levelled. It was in the bruary, when those birds usually was applied to the but, the wed into the opening, the woods e blows of the beetle or mall its fall; but still the dam it gave way, the bird wa though her parental fate, was whipped brought her dead

Ra genus of mytilis and the species of crista galli; called by Lister, rastellum; by Rumphius, osIt is in reality a bivalve of the Linnæan treum plicatum minus; by D'Argenville, auris lections, cock's comb. Though I applied to several such in London, I nevuld meet with an entire

specimen; nor coul graving from a p seum at Leiceste me to examine f disappointed as fer