260 THE BOTANY OF CHRISTMAS ISLAND. 



requiring to be drifted to Australia and back. Andrews points 

 out that the Ocean current which passes the island is the 

 equatorial drift which comes down from the Timor sea and 

 receives tributaries through the Straits between Bali and 

 Lombok etc. This would bring down doubtless all the Sea- 

 borne seeds of Australian types on the island. But there must 

 be also currents from the north to account for the typically 

 Javanese plants. 



The absence of many plants of which the seeds must at 

 times have reached the island is perhaps due to the unsuitabi- 

 lity of soil for them. Thus the Mangrove plants, Rhizophora, 

 Bruguiera and Avicennia the fruit of which may be seen in 

 abundance drifting down the Banka Straits are absent, Cerbera 

 odollam too seems to have failed to properly establish itself 

 though a tree of this was seen by Andrews. It seems to have 

 disappeared since. There is in fact no suitable ground for these 

 plants which require a muddy soil for their existence. Pangium 

 edule a riverbank plant, the seeds of which have been seen in 

 sea drift in other parts of the Archipelago besides Christmas 

 Island where I found one battered seed, has not succeeded in 

 establishing itself as there is no place suited for it. 



Some of the plants which have established themselves are 

 very local and only growing special soils, such are Mariscus 

 albescens, on the out crop of volcanic rock near the Waterfall, 

 and Nephrodium truncation on the mud by the fresh-water 

 stream in the same locality, both evidently plants which cannot 

 grow on the coral reefs or their detritus. 



The great height of the cliffs surrounding the island for its 

 greatest part would also militate against the successful landing 

 of sea-drifted seeds. There are as far as is known only two or 

 three possible landing places for such plants, Flying Fish Cove, 

 the Waterfall bay and a few smaller beaches beyond, the West 

 white beach and a few other possible spots, but in former years 

 there may have been other suitable spots, and during the 

 Monsoon the waves beat up very high on parts of the coast, and 

 seed might be thrown to the top of many of the lower cliffs. 



During my stay in Christmas Island I looked for fruits 

 and seeds washed ashore in the bays but could find very few. 



Jour. Straits Branch 



