40 



A NATUBALIST'S WANDEIilNOS 



what seemed to me signs of recent elevation. At ebb tide 

 there the ivater was very shallow and quite warm to the band, 

 and I noticed Ostrmtd^, small Tridaenm and other slielJs all 

 deiid where they grew, doubtless killed by expf>siire to the sun at 

 low tide and by the fresh water during heavy rains. Of these 

 tropical downpours, Darwin records one as having taken plaee 

 before his visit, and Mr. B<JS3 told me that in 1866, there were 

 several months of snch continuous rain that the fresh water 

 stood for several inches on the surface of the lagoon, causing the 

 death of large numbers of fish, and no doubt of corals also. 



Completely surrounding this little islet was a thrown-up 

 beach of very white sand, quite different from that I saw 

 anywhere else on the atoll, composed entirely of the minute 

 shells of molluscs, Echini, and of cmbs, with a small proportion 

 of coral dehriSf probably raised by the waves from the seaward 

 slope of the barrier, indicating, perhaps, a less abrupt deswnt 

 than has been supposed. Since its first occupation (by Eoss 

 Primus) the lagoon has greatly filled up witli coral patches and 

 sediment, as he could sail his vessel much farther up towards 

 South-east Island than now, and several boat channels cut as 

 kidicated on the map have become quite obliterated. On the 

 east side of the atoll the islets are much smaller than at any 

 other part, and this may result if such an untoward circum- 

 stance as the irruption of poisoned water, such as I have 

 recorded above, were to occur at frequent intervals. It is 

 possible also that such a stream might issue frequently, if not 

 in great quantity, without being observed, 



I incline to believe, therefore, that the Keeling reef 

 foundation has arisen as Blurray, Semper and Agassiz have 

 suggested ; but that its islets have been the result of the 

 combined action of storms and the slow elevation of the vol- 

 eunically upheaved ocean floor, on which the reef is built,* 



The atoll offers to the nafuine biologist a rich mine that 

 would take not a few years of working to exhaust ; f to the 



* An abstract of an exhaustive resum^ and discussion by I>r. A, Geikie, 

 F,R,S., of the Coral Reef iheoriee will be fotipd in Art?«rr^ Nov. 29 anti Dec, ti, 

 1883, of which the fiiU text has just been published in the Prac. Phtfs. Soc> 

 Iltfm,, vol, riii, (1884). 



t I have el&ewhere (Proc, R. (?- 8., Majich 1884) ilirected al tcntion 1o the 

 aiiinirahie tsiiuation of this s|k»1 for a BiirlctgicAl aud MetLomlogicjil Statiuu, 

 where it could he kept up at the most triflkig cost. 



