84 BULLETIN: MUSEUM OF COMPARATIVE 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 Gardiner 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 with 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 the 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. 
2 Proc. Camb. Phil. Soc., Vol. IX, Pt. VITI., 1898, pp. 480, 431. 
8 Loc. cit., p 454. 4 Loe. cit., p. 488. 
6 Memoir III., Australian Museum, Part I. Sydney, 1896. 
