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DR. H. B. GUPPY. 
“PRELIMINARY NOTE” ON THE KEELING ATOLL. 
By H. B. Guppy. 
After Mr. Guppy had read the foregoing paper before the 
Institute he left England to explore the Keeling Atoll, known _ 
also as the Cocos Islands, and through the courtesy of 
Messrs. Macmillan, the proprietors of Nature, the Institute is 
enabled to insert his “ preliminary note” to Mr. John Murray, 
thereon :— 
During my sojourn of nearly ten weeks in these islands, I was 
able to make a fairly complete examination of them. Here I can 
only refer to some of the new features of this atoll which my 
investigations have disclosed, and must leave the details to be sub- 
sequently worked into a general description of the islands. 
Regarding myself as very fortunate in being able to examine the 
only atoll visited by Mr. Darwin,—the atoll, in fact, which gave 
rise to the theory of subsidence, —I at once set about making obser- 
vations, without reference to any particular view of the origin of 
coral reefs. I examined all the islands and islets, more than twenty 
in number, making a separate description of each, and reaped the 
benefit of the fact that this atoll had ‘been occupied for more than 
half a century by residents interested in their surroundings. The 
result has been to convince me that several important characters of 
these islands escaped the attention of Mr. Darwin, partly owing to 
his limited stay, partly also due to his necessarily defective infor- 
mation of the past changes in the atoll. The features, in fact, that 
escaped his notice, throw considerable light on the mode of origin 
of these lagoon islands, and give no support to the theory of 
subsidence. 
In the first place, I have ascertained that Keeling Atoll consists 
essentially of a ring of horse-shoe or crescentic islands, inclosing a 
lagoon, and presenting their convexities seaward. The crescentic 
form is possessed in varying degrees by different islands; some of 
the smaller ones are perfect horse-shoe atollons, and inclose a shallow 
lagoonlet ; others, again, exhibit only a semi-crescentic form ; whilst 
the larger islands have been produced by the union of several islands 
of this shape. The whole land surface, however, is subject to con- 
tinual change. The extremities of islands are often being gradually 
swept away or extended. Some islands are breached during heavy 
gales, others are joined, so that by the repetition of these changes 
