ON THE SEA-SHORE. 255 



teristic buttresses. Here we have a suggestion of 

 the pile so well known in connection with bridge 

 building. However ancient the lake dwellers may 

 have been, there can be little doubt that the man- 

 grove learnt this little bit of engineering long 

 before them. Then, in the cluster of sprawling but- 

 tresses we have the same contrivance which is used 

 to support beacons, and here also the tree was first 

 in the field. The contrivance of the courida is a 

 fascine dam far more perfect than anything erected 

 by man, as it cannot decay. When a man invents 

 a thing of this kind we honour him for his ingenuity; 

 what shall we say of the tree ? 



We must not leave the mangrove and courida 

 swamp without calling attention to the fact that 

 very few plants can endure salt water about their 

 roots for even a few hours without serious injury. 

 Besides the two species we have been considering, 

 there are, however, several others all more or less 

 fitted to the shore. The most conspicuous is the 

 Laguncularia, which assists the courida, but is not 

 so highly developed ; after that we may mention 

 the handsome Thespesia populnea with its hibiscus- 

 like flowers. Beyond these the number that revel 

 in salt water is small, and for this reason we do 

 not get that variety in the courida bush which is 

 so conspicuous in the forest proper. It is such a 



