BY C. HEDLEY. 457 



the arrest of subsequent influx. A continuation of the process 

 builds the rock upwards. Like a stalactite, the coral-sand-rock 

 derives its substance from a superincumbent mass of lime. I 

 suggest that the coral-sand-rock can only form beneath a thick 

 cover of sand, and that slow growth of the bank will provide for 

 the increase of the rock. Briefly, the coral-sand -rock is the 

 petrified core of beach or dune. 



The islet was chiefly made of coarse sand. It may be laid 

 down as a rule that, the further from the reef edge an islet is built, 

 the finer are the materials of which it is composed. 



A pit we sunk in search of water passed through foraminiferal 

 sand with lumps of coral; it was bone-dry at a depth of eight feet. 

 There was no surface water at the date of our visit. 



For the most part the islet is fringed with Casuarina trees,, 

 whose weeping boughs overhang the water at high tide. Behind 

 the shelter of these pioneers grow bushes of Tournefortia, Sophora 

 and Pandanus, with grass and herbage of Abutilon, Wedelia, 

 Ipomaea, &c. Further in the bushes become trees, and the 

 grass and herbage disappear. The centre of the islet is over- 

 grown by a dense Pisonia forest, forty or fifty feet in height, 

 whose foliage completely screens the ground from the sunlight 

 and strews it with fallen leaves. Among these were concealed 

 two snails, a Bifidaria and a Tornatellina. The contrast between 

 the cool shade within and the heat and glare of the beach is very 

 sudden. 



This islet is a refuge and breeding ground for sea-fowl. Some 

 frigate birds were shot on the wing. The reef herons were 

 hatching in the Sophora boughs. The noddy terns crowded the 

 trees with nests. Fearless in their ignorance of man, they 

 permitted us to approach them on their nests, but would not 

 submit to be handled. The sooty petrels hurrying seawards before 

 dawn, where our party slept across their track, would climb over 

 our bodies as if we were logs of wood. By day and night the 

 bush resounded with the hoarse cries of the sea-birds. The 

 turtles were so plentiful that we never walked around the beach 

 without seeing one. On a moonlight night I have passed twenty 

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