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demonstration, all that I have to offer in support of my 

 opinion are arguments founded on probability and analogy. 



" If we may judge from the form and structure of the 

 coralline productions, the number of species endowed with 

 the power of fabricating them must be very considerable. 

 All of them agree, however, in one respect ; they commence 

 their work at a central point, and extend it in all directions 

 indiscriminately. The law which governs the operations of 

 an individual or a family in this respect, is no doubt equally 

 operative on the whole society ; and the aggregate ought to 

 exhibit, on reaching the surface, a reef of a circular form, 

 and coextensive at least with the base whereon it rests. 

 But Coral-reefs rarely exhibit this form, or any other that 

 can be easily defined. Their forms are usually the most 

 irregular that can be imagined ; such, indeed, as can only be 

 attributed to a corresponding irregularity in the base on which 

 they are reared. 



" The coral-worms build perpendicularly, and only on a 

 fixed solid foundation. This is well exemplified in the Island 

 of Bourbon ; where a deep, precipitous, rocky coast on one 

 side, and on the other, a shelving shore of water-worn 

 pebbles, have hitherto prevented the establishment of these 

 fabrics. The fact, too, that harbours and the mouths of 

 rivers in tropical regions are invariably clear of living coral, 

 though liable to be choked up with its debris, is illustrative 

 of the same principle. 



" If the Coral-reefs were built up from the bottom of the 

 sea, how are we to account for the partial manner in which 

 they are distributed ? The shores of intertropical continents 

 and islands are generally fringed with them; and we find 

 them running in interrupted chains from one groupe of islands 

 to another, in the same manner as submarine rocks are 

 known to do in those parts of the sea that lie beyond the 

 range of the coral-worms ; but the ocean at large, is, as far 

 as we know, entirely clear of them. 



" Detached reefs are sometimes met with, of very small 

 superficial extent, one hundred yards, or perhaps less. Are 

 we to believe that a columnar mass of such fragile materials, 



