144 BULLETIN OF THE 



exterior of the reef, or else they would soon obliterate all traces of 

 the lagoon. Yet I can hardly see that he has made out a case, that 

 the corals on the outside of a lagoon on the face of a reef, in full expos- 

 ure to oceanic currents, laden with food, are not infinitely better off, and 

 naturally grow more vigorously, than tliose which, as in a lagoon, are cut 

 oif from a great part of their food supply. They are able to grow in 

 lagoons in spite of this, because they grow in localities which are kept 

 clean. As I have plainly shown in the Tortugas, all corals grow i-emark- 

 ably well on the edge of channels, above the sand drifted by the waves 

 and currents inland. 



The following observations on the Coral Reefs of the Sandwich Islands 

 were made in the winter of 1885, and formed the substance of a lecture 

 delivered at Honolulu during my stay there. I have to thank Prof. W. 

 D. Alexander for important assistance during my visit, and for the com- 

 munication of valuable information from the ai'chives of the Surveyor 

 General's Office. Prof James D. Dana has given an admirable account 

 of the elevated coral reefs of Oahu, and of the extent of the distribution 

 of reefs on the Hawaiian group. Brigham has also added many interest- 

 ing observations on the coral reefs of the Sandwich Islands, and Captain 

 Button in his exploration of the group noted incidentally some points 

 bearing on the subject. Couthouy has also given a description of the 

 elevated coral reefs of the vicinity of Honolulu, as well as of the ele- 

 vated beaches of Kauai. ^ My own observations supplement those of 

 Dana. I have gone over very much the same ground he covered in 

 1843, limiting myself, however, to the examination of the reef area 

 proper, as far as it includes the living and the elevated reefs of the 

 islands which I visited, — Oahu, Maui, and Hawaii. For my knowl- 

 ed^re of the reefs on the other islands I am indebted to the observations 

 of Couthouy, Dana, and of Brigham. 



All investigators of coral reefs agree that corals grow in greatest per- 

 fection in the comparatively still waters of inner channels. Thus, in the 

 Tortugfas, the largest masses of Mseandrinas and Astrseans are found in 

 the old channels between formerly distinct reefs, while the great coi'al 

 heads, measui'ing no less than twelve to fifteen feet in diameter, reach 

 their maximum size in the so-called ship channel between the outer 

 reef of Florida and the line of the Keys. As in Florida, so in the 

 Sandwich Islands, the most luxurious growth of Madrepores occurs upon 

 the face of the inner channels. There are, for instance, huge masses of 



1 Coutliouy, Joseph P., Remarks upon Coral Formations in tlie Pacific, Journal 

 Bost. Hoc. Nat. Hist., 1842, p. 146. 



