xed up with sand, clay,
and other extraneous matters, on some of the commoner molluscs of our
shores; and universally found that the mass, incoherent everywhere
else, had acquired solidity wherever it had been permeated by the
animal matter of the molluscs. Each animal, in proportion to its size,
is found to retain, as in the fossiliferous spindles of the Old Red
Sandstone, its coherent nodule around it. One point in the natural
phenomenon, however, still remains unillustrated by the experiments of
Mrs. Marshall. We see in them the animal matter giving solidity to the
lime in immediate contact with it; but we do not see it possessing any
such affinity for it as to form, in an argillaceous compound, like that
of the ichthyolite beds, a centre of attraction powerful enough to draw
together the lime diffused throughout the mass. It still remains for the
geologic chemist to discover on what principle masses of animal matter
should form the attracting nuclei of limestone nodules.

The declining sun warned me that I had lingered rather longer than was
prudent among the ichthyolites of Clune; and so, striking in an eastern
direction across a flat moor, through which I found the schistose gneiss
of the district protruding in masses resembling half-buried boulders, I
entered the forest of Darnaway. There was no path, and much underwood,
and I enjoyed the luxury of steering my course, out of sight of road and
landmark, by the sun, and of being not sure at times whether I had skill
enough to play the part of the bush-ranger under his guidance. A sultry
day had clarified and cooled down into a clear, balmy evening; the slant
beam was falling red on a thousand tall trunks,--here gleaming along
some bosky vista, to which the white silky wood-moths, fluttering by
scores, and the midge and the mosquito dancing by myriads, imparted a
motty gold-dust atmosphere; there penetrating in straggling rays far
into some gloomy recess, and resting in patches of flame, amid the
darkness, on gnarled stem, or moss-cushioned stump, or gray beard-like
lichen. I dislodged, in passing through the underwood, many a tiny
tenant of the forest, that had a better right to harbor among its wild
raspberries and junipers than I had to disturb them,--velvety
night-moths, that had sat with folded wings under the leaves, awaiting
the twilight, and that now took short blind flights of some two or three
yards, to get out of my way,--and robust, well-conditioned spide