execute in the Antarctic latitudes the office of our trees and grass turf
in the temperate regions, and the broad leaves of the palm, &c., in the
tropics." ...

With respect to the distribution of the _Diatomaceoe_, Dr. Hooker
remarks:--

"There is probably no latitude between that of Spitzbergen and Victoria
Land, where some of the species of either country do not exist: Iceland,
Britain, the Mediterranean Sea, North and South America, and the South
Sea Islands, all possess Antarctic _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 phonolite
stones of the Rhine, and the Tripoli stone, contain species identical
with what are now contributing to form a sedimentary deposit (and
perhaps, at some future period, a bed of rock) extending in one
continuous stratum for 400 measured miles. I allude to the shores of the
Victoria Barrier, along whose coast the soundings examined were
invariably charged with diatomaceous remains, constituting a bank which
stretches 200 miles north from the base of Victoria Barrier, while the
average depth of water above it is 300 fathoms, or 1,800 feet. Again,
some of the Antarctic species have been detected floating in the
atmosphere which overhangs the wide ocean between Africa and America. The
knowledge of this marvellous fact we owe to Mr. Darwin, who, when he was
at sea off the Cape de Verd Islands, collected an impalpable powder which
fell on Captain Fitzroy's ship. He transmitted this dust to Ehrenberg,
who ascertained it to consist of the silicious coats, chiefly of American
_Diatomaceoe_, which were being wafted through the upper region of the
air, when some meteorological phenomena checked them in their course and