88 



ZOOLOGY. 



the sea. The reefs are often of great thickness, for, as 

 Dana says, " could we raise one of these coral-bound islands 

 from the waves, we should find that the reefs stand upon 



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the submarine- slopes, like massy structures of artificial 

 masonry ; some forming a broad flat platform or shelf 

 ranging around the land, and others encircling it like vast 



