reous deposit of a brick-red color. In this red
deposit are shells, or often the hollow casts of shells, chiefly
referable to eight or nine species of land snails, a few scattered bones
of quadrupeds, and, what is still more singular, marine univalve shells,
often at the height of many hundred, or even one thousand feet above the
sea. The following explanation is given of the gradual increase of this
deposit. Land snails of the genera Helix, Cyclostoma, Pupa, and
Clausilia, retire into the caves, the floors of which are strewed with
myriads of their dead and unoccupied shells, at the same time that water
infiltered through the mountain throws down carbonate of lime,
enveloping the shells, together with fragments of the white limestone
which occasionally falls from the roof. Multitudes of bats resort to the
caves; and their dung, which is of a bright red color, (probably derived
from the berries on which they feed,) imparts its red hue to the mass.
Sometimes also the Hutia, or great Indian rat of the island, dies and
leaves its bones in the caves. "At certain seasons the soldier-crabs
resort to the sea-shore, and then return from their pilgrimage, each
carrying with them, or rather dragging, the shell of some marine
univalve for many a weary mile. They may be traced even at the distance
of eight or ten miles from the shore, on the summit of mountains 1200
feet high, like the pilgrims of the olden times, each bearing his shell
to denote the character and extent of his wanderings." By this means
several species of marine testacea of the genera Trochus, Turbo,
Littorina, and Monodonta, are conveyed into inland caverns, and enter
into the composition of the newly formed rock.

CHAPTER XLVII.

IMBEDDING OF ORGANIC REMAINS IN SUBAQUEOUS DEPOSITS.

Division of the subject--Imbedding of terrestrial animals and
plants--Increased specific gravity of wood sunk to great depths in
the sea--Drift-timber of the Mackenzie in Slave Lake and Polar
Sea--Floating trees in the Mississippi--in the Gulf Stream--on the
coast of Iceland, Spitzbergen, and Labrador--Submarine
forests--Example on coast of Hampshire--Mineralization of
plants--Imbedding of marine plants--of insects--of reptiles--Bones
of birds why rare--Imbedding of terrestrial quadrupeds by river
floods--Skeletons in recent shell marl--Imbedding of mammiferous
remains in marine strata.

_Division of the subject._--Having treated of