CONTENTS. 



Introduction page 1 



CHAPTEK I. 



ATOLLS OR LAGOON ISLANDS. 



Section I. — Description of keeling atoll. 



Corals on the outer margin — Zone of Nulliporae — Exterior reef — Islets — 

 Coral-conglomerate — Lagoon — Calcareous sediment — Scari and Ho- 

 luthurise subsisting on corals — Changes in the condition of the reefs 

 and islets — Probable subsidence of the atoll — Future state of the 

 lagoons 7 to 26 



Section II. — General description of atolls. 



General form and size of atolls, their reefs and islets — External slope — 

 Zone of Nulliporse — Conglomerate — Depth of lagoons — Sediment — 

 Eeefs submerged wholly or in part — Breaches in the reef — Ledge- 

 formed shores round certain lagoons — Conversion of lagoons into 

 land 27 to 43 



Section III. — Atolls of the maldiva archipelago — 



GREAT CHAGOS BANK. 



Maldiva Archipelago — Eing-formed reefs, marginal and central — Great 

 depth in the lagoons of the southern atolls — Eeefs in the lagoons 

 all rising to the surface — Position of islets and breaches in the reefs, 

 with respect to the prevalent winds and action of the waves — Des- 

 truction of islets — Connection in the position and submarine foun- 

 dation of distinct atolls — -The apparent disseverment of large atolls — 

 The Great Chagos Bank — Its submerged condition and extraordinary 

 structure . 43 to 55 



