84 bulletin: museum of compaeative zoology, 



I take it that the " cliffs " mentioned by Sollas,^ and that the pinna- 

 cles described by Gardiner ^ which he calls " the remains of a part of an 

 old raised reef," found on the inner rough zone of the outer reef, are just 

 such masses of tertiary limestone as we found throughout the Fijis. 



The shoals described by Gardiner ^ seem to me to be remnants of this 

 elevated reef which have been isolated by submarine erosion, much as 

 iu Fulanga and Ngele Levu, and other groups of elevated tertiary lime- 

 stone reefs in Fiji, upon which corals grow with greater or less luxuri- 

 ance, the bottom of the lagoon between the patches and knolls being 

 covered with sand. 



Gardiner* supposed the atoll of Funafuti to have been formed before 

 it was elevated. If I am correct in my interpretation of similar reefs 

 in Fiji, I think, on the contrary, that the low limestone outer platform 

 which now forms the ring of the atoll was once much higher, covered 

 a greater area, and has been gradually denuded and eroded to its present 

 stage, a process which according to Gai-diner and my own observations is 

 still going on. 



Hedley,^ as well as Sollas and Gardiner, assumes an elevation of four 

 feet from the presence of dead subfossil corals in the position of life 

 near high water mark. I do not see why the fact that the older lime- 

 stones of Funafuti form a cone, and have no connection witli the recent 

 reef formed upon them, should have any bearing either in favor of or 

 against any theory of coral reefs, even if the formation of the corallif- 

 erous limestones of Funafuti could only be explained on the subsidence 

 theory. The lateral growth of the recent reef inwards and outwards is 

 a feature depending, so far as the outer growth is concerned, wholly 

 upon the exterior slope of the atoll, and the lateral expansion towards 

 the interior of the lagoon depends upon a great variety of causes, such 

 as the depth of the lagoon, the character of the islands on the outer edge 

 of tlie atoll, the nature and depth of the shallower windward passages 

 leading into the lagoon, the position of the outer reefs with reference to 

 the prevailing winds and currents, the geological structure of the sub- 

 stratum upon which the recent reef is growing, and many other causes. 

 As far as the filling of the lagoon of Funafuti is concerned, the views of 

 Gardiner and Hedley are diametrically opposed. The islands may in- 



1 Proc. Royal Society of London, March, 1897, p. 502. Nature, September 24, 

 1896. p. 517. ' 



•^ Proc. Camb. Phil. Soc, Vol. IX. Pt. VIII., 1898, pp. 430, 431. 



3 Lnc. cit., p 434. * Loc. cit., p. 438. 



^ Memoir III., Austrahan Museum, Part I. Sydney, 1896. 



