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downwards from the higher mountains to the lower districts, and, by this progressive motion, carried with them the masses of stone which they had torn from the mountains. It is easy to explain why no trace of these masses thus separated is to be found immediately below the precipices thus formed.

As these mountain precipices are often from three, four, to five thousand feet high, and the valleys over which they hang are likewise several thousand feet in breadth, it must be a matter of astonishment to think of such valleys being filled with ice to the extent of several miles. This ice in lower districts must have stretched a long way out into the sea, and, on its thawing, large masses must have broke loose, and gone out to sea, as we find takes place now in the polar regions. I have no hesitation in affirming this, when I survey the effects of immense masses of ice, where there is no room to be mistaken.

I shall further mention the supposed effects of glacier ice in another part of Norway, at the level of the sea.

Last summer I went by sea from Bergen to Söndfiord and Nordfiord, on the outside of the Scars (the rocks which lie along the shore), to examine the petrifactions which Pontoppidan talks of in his Natural History of Norway, as to be found in Steensund, in the island of Gulé, at the beginning of the 61° of north latitude. I went on shore at different places; and although I carefully examined every place around, I found not a trace of petrifaction.* On the contrary, I found that the part of the continent separated from it by the Sound, and the island of Inner or Easter Lulé, consisted of a solid conglomerate, composed of boulders, from the size of a pea to that of a man's head. These boulders consisted chiefly of gneiss, quartz, and clayslate, which were involved and bound together in a mass so solid, that it was difficult to find out what the binding medium was, as the interstices between the large stones were completely filled up with small boulders. On closer examination, at particular spots, I found that this binding medium was chlorite and hard clay.

* Professor Rathke, who had formerly been at the same place, and found none, recommended to me to make this examination.

On this rock there seemed to me proofs of the powerful operation of ice. I found that the precipices on the side of the mountain next the Sound were several feet in height, and perfectly perpendicular ; and though they were composed, as I have mentioned, of boulders cemented together, they were perfectly even and smooth. If these precipices had been the effect of rents, attended with successive masses tumbling down, then the boulders adjoining the rent must have been found adhering sometimes to the one and sometimes to the other of the separated masses, (those which have fallen into the sea are no more to be seen); and, in that case, the boulders left in one mass must have left a mark of itself in the corresponding one. This, however, was by no means the case, as the rock which remained was perfectly smooth, and had the appearance as if these boulders had been cut across by a sharp knife. I can explain this phenomenon in no other way than by supposing, that large masses of ice pressing through the Sound, have cut these precipices lying parallel to the direction of the Sound.

I could give other proofs of the conclusion I have sought here 10 establish, but, to persons capable of judging of the matter, I consider these as sufficient.

The result of what I have said I may state in the following particulars.

1. That, in the beginning, the earth existed in a fluid state.

2. That, during the long period it required to assume its proper composition and form, it has alternately been, at one time, at such a distance from the sun, that all the water upon

it must have necessarily been converted into ice ; at another so near it, that not only the solid earth and minerals underwent a change, but also the fluid substance which held them in solution was decompounded and changed. How deep these changes went into the body of the earth we have yet no means of ascertaining. By comparing the phenomena of burning volcanoes with the combustion of the metalloids, kalium, natrium, silicium, calcicum, we may conclude, that, deep in the bowels of the earth, there is to be found a multitude of specific metalloids, the combustion of which is the cause of the eruptions of volcanoes.

3. That organisation did not begin till this long period was

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completed, which the earth required to the full development of its own constitution; that, after it began, it proceeded by successive steps from the less to the more perfect formations, ending with man as the head of the whole.

Observations on the Structure and Functions of the Sponge.

By R. E. GRANT, M. D., F. R. S. E., F. L. S., M. W. S., Honorary Member of the Northern Institution, &c. Communicated by the Author. Concluded from the preceding

Volume, p. 351. (With a Plate.) The silicious and calcareous spicula'above described are group ed into strong fasciculi, which are disposed around the internal canals of the sponge, in the order best calculated to defend these passages from compression, and from the entrance of extraneous bodies, and likewise to form between the canals certain interstitial spaces for the development and exit of the ova. Like the hard parts composing the skeleton in other animals, these earthy spicula are maintained in their relative situations by a tough ligamentous matter, distinct from the other soft parts of the sponge. In the horny species, however, where the axis is composed of cylindrical tubular horny fibres, ramified and continuous throughout the whole body, this connecting cartilaginous matter appears to be unnecessary, and, from the examination of dried specimens, it appears to be altogether wanting. The examination of the living properties of the axis in the horny species forms a subject of curious and interesting inquiry, which must be left to those who have opportunities of observing them alive in warmer latitudes, as they do not seem to inhabit the British shores. The dried filaments of the S. fistularis, Lam. when viewed through a powerful microscope, appear to consist of one continuous ramified tube, whose central cavity (Pl. II. Fig. 19. 6) is entirely filled with a dark opaque granular matter, which does not consist of spicula, while the sides of the tube (a) are transparent and amber coloured like common cat gut. In the S. officinalis, where the filaments are much finer, the sides of the tube (Fig. 20. a) have the same colour and homogeneous appearance, but the central cavity (6) appears empty. Mr Ellis states,

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