y2 THE WORLD. 



successive fleshy mass expires, a new one appears, which gradu- 

 ally expands and deposits its calcareous secretions upon the old 

 one, and thus vast beds of stony matter are accumulated in the 

 bottom of the sea, and become the foundations of coral reefs and 

 islands. " We may compare" observes Mr. Lyell, " the opera- 

 tion of these zoophytes in the ocean to the effects produced on a 

 smaller scale upon the land by the plants which generate peat. 

 In the case of the Spagnum, (page 204), the upper part vege- 

 tates while the lower portion is entering into a mineral mass, in 

 which the traces of organization remain, when life has entirely 

 ceased. In corals, in like manner, the more durable mate- 

 rials of the generation that has passed away, serve as the founda- 

 tion on which living animals are continuing to rear a similar 

 structure." The Caryophilla, or branched star-like coral, is an- 

 other common species. We give an engraving of an American 

 specimen as it appears when alive. The three branches, each 



contain a bright green polypus. The Astrea, is another very 

 common and extensive species of coral, fig. 1, represents the 



coral as seen alive in the sea. the polypi are of a dark green 



