ON CORAL REEFS OF TBE INDIAN REGION. 307 



&c. are mentioned, will be, I trust, useful for a further comparison when- 

 ever the group is resurveyed by the Admiralty. 



As the results of the expedition on the question of the formation of 

 coral reefs, the inAestigatioii of which was the main object of the expedi- 

 tion, have now been published, I may be permitted to briefly summarise 

 them.^ I would, however, first express my very great indebtedness to 

 Messrs. L. A. Bori-adaile and C. Forster Cooper and Captain Molony, of 

 the ss. ' Ileafaee ' for the very loyal and whole-hearted way in which they 

 aided me in all the work. 



In the first place, an accurate knowledge has been obtained of the 

 largest and most extraordinary series of coral formations in the world, 

 one situated too at the preseiit time quite outside the influences of conti- 

 nental conditions. The physical features of the region have been examined, 

 especially in respect to currents, while the biological conditions have been 

 exhaustively studied both of the encircling reefs and of those within the 

 banks, and both towards the ocean and the enclosed waters of the lagoons 

 and banks. Owing to specially favourable circumstances it has been pos- 

 sible to throw considerable light on the rate of growth of corals and hence 

 also of reefs. Special work was undertaken to investigate the seaward 

 slopes of the reefs, the formation of lagoons, the action of boring and 

 sand-feeding organisms, and the conditions affecting the land. Owing to 

 this examination it has been possible to ascertain the changes in progress 

 in the different atolls and banks, and so by deduction to infer the later 

 stages in the formation of the coral reefs of the region. 



Unfortunately the means available for the expedition were nofc 

 sufficient to allow of detailed work being undertaken below 50 fathoms, 

 which was shown to be the extreme limit in depth of the so-called reef- 

 building corals, those forms which at present are found living on the 

 surfaces of the reefs. '^ A few deeper soundings were nevertheless made, 

 showing in the centre of the Maldive group a comparatively shallow 

 (200 fathoms) table on which the majority of the atolls and banks have 

 arisen. A subsequent expedition by that renowned American investigator 

 Professor Alexander Agassiz has further elucidated the greater depths, 

 and its full report, when published, will probably be found to give a very 

 complete idea of the whole topography of the Maldive Archipelago. 



While a fair knowledge has now been attained of the conditions and 

 life on the floor of the deep sea, there has unfortunately been little work 

 done in oceanic areas on the shallower bottom down to 500 fathoms. The 

 evidence from the Maldive group shows how peculiarly interesting would 

 be such a knowledge of the conditions between 50 and 200 fathoms. 

 Indeed, an expedition undertaken mainly for this object would certainly 

 do more to elucidate the probable and possible methods of the formation 

 of coral reefs than any other mode of investigation. Further, such an 

 expedition would undoubtedly throw an immense flood of light on the 

 bathymetrical distribution of animals and plants. It would also make 

 possible a proper examination into the questions relating to the geographical 

 distribution of marine animals and plants, a subject at present untouched, 



' See also 'The Origin of Coral Eeefs as shown by the Maldives,' by .J. Stanley 

 Gardiner, Amcr. Journ. Sol., vol. xvi., Sept. ] 903, pp. 203-213. 



2 These forms depend mainly on their commensal alga; for their nutrition, but 

 the existence of a perfectly distinct coral fauna living at intermediate depths, having 

 Us maximum luxuriance at about 40 fathoms, and not depending on coiEvjensal alga-, 

 was discovered. 



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