THE CQALENTERATES 43 
Nearly all species, like the sea-anemones, are brilliantly 
colored during life, and several are highly phosphorescent. 
All are marine, and while they are found everywhere, from 
the shore-line to great depths, the more abundant and 
larger species inhabit the clear, warm waters of the tropics 
down to a depth of one hundred and sixty feet. In such 
regions the stag-horn corals especially grow in the wildest 
profusion, and become tall and greatly branched. Except 
in quiet water they are continually being broken by the 
waves, beaten into fragments, and the resulting sand is 
deposited about their bases. As a result of this continu- 
ous growth and erosion, there have been formed from coral 
sand mixed with the shells of mollusks and the skeletons 
of various Protozoa several of the islands along the Florida 
coast and many of those of the Pacific, some of them 
hundreds of miles in extent. 
