Hence it follows that these silicious organisms, though they are not heavier than the lightest dust, must have fallen, in some cases, through fifteen thousand feet of water, before they reached their final resting-place on the ocean floor.

Imbedded in the chalky mud of the deep sea, in many localities, are innumerable cup- shaped sponges, provided with six-rayed silicious spicula, so disposed that the wall of the cup is formed of a lacework of flinty thread.

Dr. Dickie, of Aberdeen, sent these materials to Ehrenberg, who made out that the residuum of the melted ice consisted for the most part of the silicious cases of diatomaceous plants, and of the silicious spicula of sponges; while, mixed with these, were a certain number of the equally silicious skeletons of those low animal organisms, which were termed Polycistineoe by Ehrenberg, but are now known as Radiolaria.

Off Victoria Barrier (a perpendicular wall of ice between one and two hundred feet above the level of the sea) the bottom of the ocean was covered with a stratum of pure white or green mud, composed principally of the silicious shells of the Diatomaceoe.

The silicious coats of species only known living in the waters of the South Polar Ocean, have, during past ages, contributed to the formation of rocks; and thus they outlive several successive creations of organized beings.

The species of Diatoms entering into this deposit have not yet been worked up, but they appear to be referable chiefly to the genera Fragillaria, Coscinodiscus, Choetoceros, Asteromphalus, and Dictyocha, with fragments of the separated rods of a singular silicious organism, with which we were unacquainted, and which made up a large proportion of the finer matter of this deposit.

By far the most abundant was the little bundle of silicious rods, fastened together loosely at one end, separating from one another at the other end, and the whole bundle loosely twisted into a spindle.

Like the Globigerina ooze, then, which it succeeds to the southward in a band apparently of no great width, the materials of this silicious deposit are derived entirely from the surface and intermediate depths.

Thus, in the whole of the "intermediate zone," the silicious deposit which is being formed there, as elsewhere, by the accumulation of sponge- spicula, Radiolaria, and Diatoms, is obscured and overpowered by the immensely greater amount of calcareous sediment, which arises from the aggregation of the skeletons of dead Foraminifera.

For the present we must be content with the fact that, in certain areas of the "intermediate zone," greensand is replacing and representing the primitively calcareo- silicious ooze.

"It is impossible to avoid associating such a formation with the fine, smooth, homogeneous clays and schists, poor in fossils, but showing worm- tubes and tracks, and bunches of doubtful branching things, such as Oldhamia, silicious sponges, and thin-shelled peculiar shrimps.

But just as a silicious deposit may be metamorphosed into opal or quartzite, and chalk into marble, so known metamorphic agencies may metamorphose clay into schist, clay-slate, slate, gneiss, or even granite.

The bearing of the conclusions which are now either established, or highly probable, respecting the origin of silicious, calcareous, and clayey rocks, and their metamorphic derivatives, upon the archaeology of the earth, the elucidation of which is the ultimate object of the geologist, is of no small importance.

And yet that rock is now forming in the midst of a sea which swarms with living beings, the great majority of which are provided with calcareous or silicious shells and skeletons; and, therefore, are such as, up to this time, we should have termed eminently preservable.

From Los Baños I had intended to go to Lupang Puti (white earth), where, judging from the samples shown me, there is a deposit of fine white silicious earth, which is purified in Manila and used as paint.

[Naglegbeng silicious springs.]

One spot, denuded of trees, from two to three hundred paces in breadth and about five hundred in length, was, with the exception of a few places overgrown with turf, covered with a crust of silicious dross, which here and there formed large connected areas, but was generally broken up into flaky plates by the vertical springs which pierced it.

The continuous deposit of dross contracts the channel, and a less quantity of water overflows, while that close to the edge of the basin evaporates and deposits a quantity of fine silicious earth; whence the upper portion of the cone not only is steeper than its base, but frequently assumes a more cylindrical form, the external surface of which on account of the want of uniformity in the overflow, is ribbed in the form of stalactites.

In the vicinity of the silicious springs are seen deposits of white, yellow, red, and bluish-grey clays, overlaying one another in narrow strata-like variegated marl, manifestly the disintegrated produce of volcanic rocks transported hither by rain and stained with oxide of iron.

These clays perhaps come from the same rocks from the disintegration of which the silicious earth has been formed.

We followed the sea-shore, which is composed of silicious sand, and covered with a carpet of creeping shore plants in full bloom.

The black copper obtained from the second operation, and the stones which were re-melted at the same time, were then subjected to a third process in the same furnace (narrowed by quarry stones and provided with a crucible); which produced a residuum of silicious iron and black copper, which was poured out into clay moulds, and in this shape came into commerce.

Some hundreds of paces further south, a hot spring (50° R.), twelve feet broad, flows from the east, depositing silicious sinter at its edges.

At some thousand paces further, the ravine bends round to the left (east), and expands itself to the bay; and here numerous silicious springs break through the loose clay-earth, which is permeated with sulphur.

To the south, right opposite to the ridge which leads to Burauen, may be seen a basin twenty-five feet broad, in a cavern in the white decomposed rock, from which a petrifying water containing silicious acid flows abundantly.