7. Anthozoa (incl. Hydrocorallia). A. Zoantharia. 37 



In describing the Ellice Islands (including Funafuti) the author does not 

 consider that subsidence has been proved to occur. - Of the Caroline 

 Islands those forming the Truk Archipelago seem at first sight to be the 

 summits, nearly denuded, of a great island which had gradually sunk. Sub- 

 sidence has played no part in bringing about the existing conditions, but sub- 

 marine erosion and other local mechanical causes provide the explanation. 

 The corals in the Carolines are mainly huge heads of Millepora, Madrepora, 

 Goniastrcea, Forties and Pavonia among which are large Alcyonaria and Acti- 

 nians. A few Mseandrinse also occur. The Porites reef flats of Apaiang 

 (Gilbert Is.) show how extensive areas covered with living corals like Porites, 

 Millepora and Potillopora are gradually changed into dead reef flats, with a 

 surface cemented by Nullipores, and become the base upon which a land rim 

 of bars or islets is gradually thrown up. Similar Mill, and Por. flats are also 

 described in Taritari (Gilbert Is.). - - See also Marenzeller( 2 ). 



Agassiz;-; describes many of the atolls of the Maldives, the pelagic fauna 

 and the bottom deposits and temperatures of the lagoons. The soundings do 

 not bear out Gardiner's statement that all the various banks of the Maldives 

 and Laccadives appear to have been built on the same set of foundations. 

 Subsidence cannot account for the formation of atolls upon banks of such 

 great difference in depth as those of the Maldives , and all within short dis- 

 tances of one another. Conditions indicate only a very slight elevation of the 

 Maldive groups, or a long stationary period, during which the faros and atolls 

 have grown to their present condition from the underlying plateau and its 

 secondary elevations. While some of the atolls (e. g. Mulaku) resemble those 

 of the Paumotus or other Pacific atolls the great land rims of the Paumotus 

 have been cut down from ledges once of a greater height, upon the outer 

 faces of which corals have grown. In the Maldives the flats are made up 

 of recent corals which have grown up from the base forming the underlying 

 plateau of the Maldives and have only been slightly elevated. In the Pacific 

 atolls the islands in the lagoon are few in number and generally the remnants 

 of the extensive denudation of somewhat more extended land areas consisting 

 of older limestone rock, while in the Maldives the islands in the lagoon are 

 often numerous and are the result of the active growth of corals now going 

 on. In none of the groups of the Maldives were found the great well-defined 

 reef platforms which are so characteristic a feature of the Pacific atolls. The 

 outer rims of the reef-flats of the Maldives are in striking contrast with those 

 of the Pacific atolls. The latter are characterised by the presence of deep 

 bays so that the exterior edge is a mass of broad digitate lobes. In the Mal- 

 dives the edge of the reef-flats is sometimes flanked by a low wall of coral, 

 or a belt of boulders or by coloured patches of corals forming a border very 

 insignificant as compared to its Pacific representative. Throughout the northern 

 and central Maldives corals grow in great profusion on the slopes of the is- 

 lands and faros within the enclosed basins of the group. The branching corals 

 consist mainly of Madrepores, Pocillipores and Millepores, while the massive 

 corals are usually Astrseans, Porites etc. Mseandrinse are not common. Living 

 Millepora was obtained from 39 fms., an unusual depth for a reef builder as 

 in the Maldives the reef corals rarely extend below 17 fms., and 12 fms. is 

 the usual depth. 



Sollas gives a general description of the atoll of Funafuti. There may 

 have been 4 changes of sea-level during the later history of the atoll. Ele- 

 vation of the atoll or fall of the sea-level to the extent of about 4 feet must 

 have occurred on the site of the mangrove swamp (and probably affected the 



