The Structure and Distribution of Coral Reefs | Page 8

by its opponents, he showed that the rival theory
presented even greater difficulties than those which it professed to
remove.
During the last five years, the whole question of the origin of
coral-reefs and islands has been re-opened, and a controversy has arisen,
into which, unfortunately, acrimonious elements have been very
unnecessarily introduced. Those who desire it, will find clear and
impartial statements of the varied and often mutually destructive views
put forward by different authors, in three works which have made their
appearance within the last year,--"The Bermuda Islands," by Professor
Angelo Heilprin; "Corals and Coral-Islands," new edition by Professor
J.D. Dana; and the third edition of Darwin's "Coral-Reefs," with Notes
and Appendix by Professor T.G. Bonney.
Most readers will, I think, rise from the perusal of these works with the
conviction that, while on certain points of detail it is clear that, through
the want of knowledge concerning the action of marine organisms in
the open ocean, Darwin was betrayed into some grave errors, yet the
main foundations of his argument have not been seriously impaired by
the new facts observed in the deep-sea researches, or by the severe
criticism to which his theory has been subjected during the last ten
years. On the other hand, I think it will appear that much
misapprehension has been exhibited by some of Darwin's critics, as to
what his views and arguments really were; so that the reprint and wide
circulation of the book in its original form is greatly to be desired, and

cannot but be attended with advantage to all those who will have the
fairness to acquaint themselves with Darwin's views at first hand,
before attempting to reply to them.
JOHN W. JUDD.
CORAL-REEFS.
INTRODUCTION.
The object of this volume is to describe from my own observation and
the works of others, the principal kinds of coral-reefs, more especially
those occurring in the open ocean, and to explain the origin of their
peculiar forms. I do not here treat of the polypifers, which construct
these vast works, except so far as relates to their distribution, and to the
conditions favourable to their vigorous growth. Without any distinct
intention to classify coral-reefs, most voyagers have spoken of them
under the following heads: "lagoon-islands," or "atolls," "barrier" or
"encircling reefs," and "fringing" or "shore-reefs." The lagoon-islands
have received much the most attention; and it is not surprising, for
every one must be struck with astonishment, when he first beholds one
of these vast rings of coral-rock, often many leagues in diameter, here
and there surmounted by a low verdant island with dazzling white
shores, bathed on the outside by the foaming breakers of the ocean, and
on the inside surrounding a calm expanse of water, which from
reflection, is of a bright but pale green colour. The naturalist will feel
this astonishment more deeply after having examined the soft and
almost gelatinous bodies of these apparently insignificant creatures,
and when he knows that the solid reef increases only on the outer edge,
which day and night is lashed by the breakers of an ocean never at rest.
Well did Francois Pyrard de Laval, in the year 1605, exclaim, "C'est
une merueille de voir chacun de ces atollons, enuironne d'un grand
banc de pierre tout autour, n'y ayant point d'artifice humain." The
accompanying sketch of Whitsunday island, in the South Pacific, taken
from Captain Beechey's admirable "Voyage," although excellent of its
kind, gives but a faint idea of the singular aspect of one of these
lagoon-islands.
(PLATE: UNTITLED WOODCUT, WHITSUNDAY ATOLL.)
Whitsunday Island is of small size, and the whole circle has been
converted into land, which is a comparatively rare circumstance. As the
reef of a lagoon-island generally supports many separate small islands,

the word "island," applied to the whole, is often the cause of confusion;
hence I have invariably used in this volume the term "atoll," which is
the name given to these circular groups of coral-islets by their
inhabitants in the Indian Ocean, and is synonymous with
"lagoon-island."
(PLATE: UNTITLED WOODCUT, REEF AT BOLABOLA
ISLAND.)
Barrier-reefs, when encircling small islands, have been comparatively
little noticed by voyagers; but they well deserve attention. In their
structure they are little less marvellous than atolls, and they give a
singular and most picturesque character to the scenery of the islands
they surround. In the accompanying sketch, taken from the "Voyage of
the 'Coquille'," the reef is seen from within, from one of the high peaks
of the island of Bolabola. (I have taken the liberty of simplifying the
foreground, and leaving out a mountainous island in the far distance.)
Here, as in Whitsunday Island, the whole of that part of the reef which
is visible is converted into land. This is a circumstance of rare
occurrence; more usually a snow-white line of great