The Dolomite Mountains. 4] 
caverns that were open or only filled with mud. Beyond twenty-five 
fathoms there was no living coral, but a bottom of coral-sand. 
Ehrenberg, when describing the corals of the Red Sea, compares 
them to forest-trees. The huge brain-corals (Meandrine) as old as 
the Pharaohs, grow upwards like living pillars, crowned with verdant 
summits, and leave a dead and petrified mass below. For it appears 
that not only do these corals fill up their own cells and cavities more 
or less, but they are further solidified by the infiltration of crystalline 
carbonate of lime, as Mr. Darwin has described in his celebrated 
Lighthouse on Uschruffee Island, Red Sea. 
a Level of high water. 6 Low-water line. c, c Coral-sand, at twenty-five fathoms. 
d Coral-rock. e,e Masses of coral expanding laterally as they approach low-water-mark, 
