1836.] LAGOON-ISLANDS, OR ATOLLS. 447 



ruins, but how utterly insignificant arc the greatest of these, when 

 compared to these mountains of stone accumulated by the agency 

 of various minute and tender animals ! This is a wonder which 

 does not at first strike the eye of the body, but, after reflection, the 

 eye of reason. 



I will now give a very brief account of the three great classes of 

 coral-reefs; namely, Atolls, Barrier, and Fringing-reefs, and will 

 explain my views * on their formation. Almost every voyager who 

 has crossed the Pacific has expressed his unbounded astonishment 

 at the lagoon-islands, or as I shall for the future call them by their 

 Indian name of atolls, and has attempted some explanation. Even 

 as long ago as the year 1605, Pyrard de Laval well exclaimed, 

 " C'est une meruille de voir chacun de ces atollons, enuironne d'un 

 grand bane de pierre tout autour, n'y ayant point d'artifico 

 humain." The accompanying sketch of Whitsunday Island in the 

 Pacific, copied from Capt. Beechey's admirable Voyage, gives but 

 a faint idea of the singular aspect of an atoll : it is one of the 

 smallest size, and has its narrow islets united together in a ring. 



The immensity of the ocean, the fury of the breakers, contrasted 

 with the lowness of the land and the smoothness of the bright 

 green water within the lagoon, can hardly be imagined without 

 having been seen. 



The earlier voyagers fancied that the coral-building animals 

 instinctively built up their great circles to afford themselves pro- 

 tection in the inner parts ; but so far is this from the truth, that 



* These were first read before the Geological Society in May, 1837, 

 and have since been developed in a separate volume on the ' Structure aud 

 Distribution of Coral Reefs.' 



