122 POPULAR ILLUSTRATIONS OF 



these Fuiigise, each corallum is separate. It is reproduced "by buds 

 or gemmules, each of which grows to a certain size, is then 

 detached, and becomes a free separate being, and forms its own 

 corallum, as " its fathers did before it." Now, were we to take a 

 number of Caryophilliae, and place them close together, we should 

 form a well-known Coral called Astrsea, as seen at Fig. 157 (frontis- 

 piece), with little or no stony substance or coanenchyma between the 

 cells ; but as some of the family like to live at a respectful distance 

 from each other, the ccenosarc secretes a ccenenchyma, as seen at 

 Fig. 167 (frontispiece). 



Now it will be seen how easily and usefully our hard words step in. 



Again, suppose that instead of having separate and distinct star-like 

 cups, as seen in Fig. 157 (frontispiece), each star was to become con- 

 fluent or join with its neighbour, we should then have the appearance 

 actually seen in the well-known "Brainstone Coral," of which a 

 figure of my specimen from Bermuda is seen at Fig. 152 (frontis- 

 piece). Of portable species this is among the largest, though they 

 are said to attain to six feet in diameter in the Bed Sea. 



At Figs. 155, 169, 158, and 159 (frontispiece), we have examples 

 of some of the common species of Madrepore, in which the cells 

 are observed to stand out in prominent relief. In Figs. 166 and 

 156 (frontispiece), the cells are noticed to be, as it were, sunk in the 

 calcareous mass of Coral. 



These last six species are among those most frequently found in 

 coral reefs, where we shall follow them in our next chapter. 



CHAPTEE IX. 

 ON CORAL ISLANDS. 



CORAL Islands and reefs are among the most interesting and remark- 

 able features on the surface of the earth, and in the natural history 

 of the world. 



Take a map of the great Pacific Ocean, and mark out a space from 

 the island of Ducie, somewhere about 120 of W. longitude, to 

 the Pellew Islands, on the line which strikes 135 E. of Greenwich. 

 Your eye will run over a great group of islands occupying a 

 space 15 north and 30 south of the equator. The space 

 thus marked out is upwards of sixteen millions of square miles, 

 and, with the exception of part of New Holland and New Guinea, 

 all the islands over which your eye will pass have been formed 



