Sect. I. 
KEELING ATOLL. 
21 
in another point of view, as showing us that there are 
living checks to the growth of coral-reefs, and that the 
almost universal law of ‘ consume and be consumed,’ 
holds good even with the polypifers forming those 
massive bulwarks, which are able to withstand the force 
of the open ocean. 
Considering that Keeling atoll, like other coral for- 
mations, has been entirely formed by the growth of 
organic beings, and the accumulation of their detritus, 
one is naturally led to enquire, how long it has con- 
tinued, and how long it is likely to continue, in its 
present state. Mr. Liesk informed me that he had 
seen an old chart in which the present long island on 
the S.E. side was divided by several channels into as 
many islets ; and he assures me that the channels can 
still be distinguished by the smaller size of the trees 
on them. On several islets, also, I observed that only 
young cocoa-nut trees were growing on the extremities, 
and that older and taller trees rose in regular succession 
behind them : which shows that these islets have very 
lately increased in length. In the upper and south- 
eastern part of the lagoon, I was much surprised by 
finding an irregular field of at least a mile square of 
branching corals, still upright, but entirely dead. They 
consisted of the species already mentioned ; they were 
of a brown colour, and so rotten, that in trying to 
stand on them, I sank half way up the leg, as if 
through decayed brushwood. The tops of the branches 
were barely covered by water at the time of lowest tide. 
Several facts having led me to disbelieve in any eleva- 
