Sect. I. DISTKIBUTION OF COKAL-REEFS. 8 1 



of the Sandwich Archipelago. In the Eed Sea there 

 are coral-reefs in lat. 30°. In the southern hemisphere 

 coral-reefs do not extend so far from the equatorial sea. 

 In the Southern Pacific there are only a few r^efs 

 beyond the line of the tropic, but Houtmans Abrolhos, 

 on the western shores of Australia, in lat. 29° S., are of 

 coral-formation. 



The proximity of volcanic land, owing to the lime 

 generally evolved from it, has been thought to be 

 favourable to the increase of coral-reefs. There is, 

 however, no foundation for this view ; for nowhere 

 are coral-reefs more extensive than on the shores of 

 New Caledonia and of north-eastern Australia, which 

 consist of primary formations ; and the Maldiva, 

 Chagos, Marshall, Gilbert, and Low Archipelagoes, 

 the largest groups of atolls in the world, are formed 

 exclusively of coral. 



The entire absence of coral reefs in certain large 

 areas within the tropical seas, is a remarkable fact. 

 Thus no coral-reefs were observed during the survey- 

 ing voyages of the Beagle on the west coast of South 

 America south of the equator, or round the Galapagos 

 Islands. It appears, also, that there are none l on this 

 coast north of the equator ; Mr. Lloyd, who surveyed 

 the isthmus of Panama, remarked to me, that although 

 he had seen corals living in the Bay of Panama, yet he 

 had never observed any reefs formed by them. I at first 

 attributed this absence of reefs on the coasts of Peru and 



1 I have been informed that this is the case, by Lieut. Eyder, R.In ., 

 and others who have had ample opportunities for observation. 



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