6 BULL?]TIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



there remain as extensive regions of possible subsidence only such isl- 

 ands as the Marshall and Carolines, some of the atolls of the Gilbert and 

 Ellice groups, and of the Paumotus. Yet, judging by analogy of the ad- 

 joining districts of Fiji and Tongn, and of the descriptions given by Dana 

 of the Paumotus, and by what we may gather from the charts in the 

 light of our own exploration, it would not be launching a very doubtful 

 proposition to assert that even in these island groups we shall find that 

 the explanations we have given of the formation of atolls and of harrier 

 reefs applies equally well to them. This still leaves the field open for 

 observations in some of the coral regions of the Indian Ocean, and of 

 the East Indian Archipelago. But in the districts which have been 

 described as typical by both Darwin and Dana, recent observations have 

 shown that other and more natural explanations than the theory of 

 subsidence are sufficient to account for the formation of atolls and of 

 barrier reefs. 



As is well known, Darwin's experience among coral reefs was limited 

 to a part of Tahiti, to the west side of Mauritius, and to the Keeling 

 Atoll. Though he passed through the Paumotus without examining 

 any of the islands ; ^ according to the narrative of the " Beagle," Darwin 

 saw in the distance Honden Island, passed by Taiaro along the shore of 

 Kauehi and sailed between Elizabeth Island and Fakarava (Wittgen- 

 stein) to Otaheite. Captain Fitzroy also sailed through the Navigator, 

 Friendly, and Fiji Islands Avithout anchoring anywhere. Dana^ worked 

 among the reefs at Tahiti, Samoa, aud the Feejees, though he did not 

 visit the Eastern Archipelago, limiting his observations to the larger 

 islands, Viti and Vanua Levu and Ovalau. He " twice visited the 

 Hawaian Islands, landed and gathered facts from fifteen coral islands, 

 some of them in the Paumotu Archipelago ; ^ one, Tongatabvi, in the 



1 Narrative of the Surveying Voyages of his Majesty's Ships Adventure and 

 Beagle (1826-18.36), Vol. III. p. 539. London, 1839. 



- In " Nature" (September 17, 1874, p. 408), Dana reviews a new edition of 

 Darwin's Coral Reefs suggesting that he had not given sufficient weight to the 

 effects of temperature in limiting the distribution of coral reefs, and differing widely 

 from Darwin as to the limits of the area of elevation and of subsidence in the 

 Pacific. But in spite of minor differences he speaks of the "array of facts of his 

 own (Darwin's) observations, which illustrate the growth of coral formation " ; and 

 subsequently, in 1885, when reviewing the whole subject again, Dana says in the 

 American Journal of Science, Vol. XXX., August-September, 1885. p. 90: "The 

 evidence which had satisfied him (Darwin) was satisfactory to me when I first 

 learned of his views in Australia (in 18.39), . . . and more decidedly later when I 

 had been among the Friendly, Feejee, and other Pacific Islands." 



3 Honden, Dean, Aratica, Ahii, Raraka, Manhii, Kawehe, ]\Ietia, Clermont 

 Tonnerre, and others examined by other members of the Exploring Expedition. 



