SHALLOW- WATER FAUNA OF THE TROPICS. 77 



Oysters and other bivalves may be found attached 

 to the roots of the trees. Several species of 

 marsh Gastropods occur, some of them in great 

 abundance in a few localities. Occasionally a 

 Sea-anemone, with remarkable powers of burrow- 

 ing rapidly in the sand when disturbed, may be 

 found, and to the microscopist a harvest of 

 Foraminifers and other minute forms of life 

 awaits investigation and description in the Man- 

 grove-swamp. 



Whenever the tide is high a considerable 

 number of Fish-fry, Jelly-fish, and other forms 

 of floating and swimming life characteristic of 

 these waters, drift into the swamps ; and some 

 being caught by the tangle of roots are left 

 behind, either in the pools, or high and moder- 

 ately dry upon the sand when the tide ebbs. 

 Upon these victims of the retreating tide swarms 

 of Ants and Flies descend from the trees, Crabs 

 from the shore and from their holes in the sand 

 are on the watch for them, Kingfishers and 

 Sandpipers are ready to pounce upon those which 

 are most to their taste, so that before the friendly 

 waters of the ocean return to the swamp, scarcely 

 one of them is left. 



These constitute what may be called in the 

 swamp the extraneous Fauna, which if it is not 

 truly indigenous is nevertheless necessary for the 

 continued existence and well-being of the true 

 inhabitants. 



The character of the sea-bottom on the outer 

 side of the living Coral-reefs varies so much in 

 different parts of the world that an adequate 

 treatment of the Fauna in that region would 



