Corals and coral islands.

4

PRElFACE.

the origin of the included channels and lagoons, and of the
distribution of reefs, together with a review of the facts with
reference to their geological bearing.
The observations forming the basis of the work were made
in the course of the cruise of the Wilkes Exploring Expedition, around the world, during the four years from 1838 to
1842. The results then obtained are published in my Report
on Zo6phytes, which treats at length of Corals and Coral
Animals, and in a chapter on Coral Reefs and Islands forming part of my Geological Report.
The opportunities for investigations in this department
afforded by the Expedition, were large. We visited a number
of the coral islands of the Paumotu Archipelago, to the north
of east from Tahiti; also, some of the Society, Navigator, and
Friendly Islands, all remarkable for their coral reefs; the
Feejee Group, one of the grandest regions of growing corals
in the world, where we spent three months; several islands
north of the Navigator and Feejee Groups, including the Gilbert or Kingsmill Group; the Sooloo sea, between Borneo
and Mindanao, abounding in reefs; and, finally, Singapore,
another East India reef-region.
Most agreeable are the memories of events, scenes and
labors, connected with the cruise:-of companions in travel,
both naval and scientific; of the living things of the sea,
gathered each morning by the ship's side, and made the study
of the day, foul weather or fair; of coral islands with their
groves, and beautiful life, above and within the waters; of
exuberant forests, on the mountain islands of the Pacific,
where the tree-fern expands its cluster of large and graceful
fronds in rivalry with the palm, and eager vines or creepers
intertwine and festoon the trees, and weave for them hangings
of new foliage and flowers; of lofty precipices, richly draped,