INTRODUCTION. 19 
mightiest operations of man! In a remote age the Egyp- 
tian kings, with a great nation at their command, built the 
pyramids which are still the wonder of the world; but the 
pyramids are but like children’s baubles compared with 
those reefs and islands, to the formation of which these tiny 
worms have even on the lowest estimate so essentially con- 
tributed. 
As the formation of coral reefs is one of the most wonder- 
ful things to which the eye of the naturalist can be turned, 
and as it is allowed by all that zoophytes contribute much 
to the mighty work, we are tempted to dwell a little on the 
subject, and to give a brief account of some of the views 
that have been taken of the matter. 
It was for some time an opinion entertained by many 
that as zoophytes cannot live at any great depth, they select 
for the commencement of their operations some favourable 
situation, such as the summit of submarime mountains ; 
and as many of the reefs are of a circular or an oval form, 
this was accounted for by supposing that the little creatures 
take as the foundation of the reef the crater of a submerged 
volcano. It will scarcely be thought that this is a very 
tenable supposition when we consider that the circum- 
ference of many of the reefs would measure from fifty to 
