6 BULLETIN: 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 Tonga, 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 barrier 
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 Hondeyw 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 without 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, Tongatabu, in the 
1 Narrative of the Surveying Voyages of his Majesty’s Ships Adventure and 
Beagle (1826-1836), Vol. III. p. 589. London, 18389. 
2 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 1839), .. . and more decidedly later when I 
had been among the Friendly, Feejee, and other Pacific Islands.” : 
8 Honden, Dean, Aratica, Ahii, Raraka, Manhii, Kawehe, Metia, Clermont 
Tonnerre, and others examined by other members of the Exploring Expedition. 
