INTRODUCTION. 
3 
faint idea of the singular aspect of one of these 
lagoon-islands. 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 sepa- 
rate 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 coral formations by 
their inhabitants in the Indian Ocean, and is syn- 
onymous with ‘lagoon-island.’ 
Barrier-reefs, when encircling small islands, have 
been comparatively little noticed by voyagers ; but 
No. 2. 
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 Bo- 
