74 THEOEY OP THEIR FORMATION. 



northern point of Eossel Island, I observed upon 

 the reefj about a hundred yards inside its outer 

 border, a series of enormous insulated masses of 

 dead coral risiag' like rocks from the shallow water. 

 The largest of these, examined through a good 

 telescope from the distance of half a mile, was about 

 twenty feet in length and twelve in height, with a 

 well-defined high water mark. It formed quite a 

 miniature island, with tufts of herbage growing in 

 the clefts of its rugged sides, and a Uttle colony of 

 black-naped terns perched upon the top as if incu- 

 bating. I had only once before seen a similar 

 exhibition of such great and permanently elevated 

 masses of dead coral upon a living reef — a pheno- 

 menon of much interest iu connexion with Mr. 

 Darwin's theory of the mode of formation of coral 

 reefs. This was on a portion of the Great Barrier 

 Reef of Australia, visited in company with Mr. 

 Jukes, who has published a detailed account of it.* 

 In both cases the only obvious explanation is that 

 these huge blocks — too massive to have been hove 

 up from deep water into their present position by 

 any storm — reached their present level by the ele- 

 vation of the sea bottom on which they were 

 formed. 



Before quitting the subject of the coral reefs of 

 the Louisiade I may be permitted to express my 

 conviction of the perfect manner in which many, 



* Voyage of H.M.S. Fly, by J. B. Jukes, vol. i. p. 340. 



