240 IN THE GUIANA FOREST. 



with wind and wave. In some respects the con- 

 trivances are similar, but here on the coast special 

 arrangements have grown up which seem to be the 

 result of long experience. Throughout the tropics 

 the same species are extending the foreshores and 

 building up islands, but little notice has been taken 

 of their work. Therefore, although neither Guiana 

 nor South America are peculiar in this respect, yet 

 they are such grand examples as to be well worthy 

 of note. From the great delta of the Orinoco to 

 that of the Amazon, the courida (Avicennia nitida) 

 and mangrove (Rhizophora Manglier) have been 

 utilising the floods and fighting the sea for ages, 

 with the result that thousands of miles of land 

 have been raised mainly by their efforts. It is 

 true that mudbanks would have been formed 

 without their aid, but every one knows how 

 unstable these are, and how liable to continual 

 shifting from tide and current. 



For fifty miles or more from the coast of Guiana 

 the sea is tinged by the thousands of tons of sus- 

 pended matter brought down from mountain and 

 forest by the great rivers. Part of this is a veget- 

 able infusion, which on coming in contact with 

 salt water is decomposed, and falls to the bottom 

 as a flocculent precipitate ; the remainder clay and 

 fine sand, which are mostly deposited on the fore- 



