SURFACE-SWIMMING FAUNA (INVERTEBRATES). 105 



it is composed of carbonate of lime instead of 

 flint. 



The Kadiolarians in some waters, and the 

 Globigerinidce in others, are present in enormous 

 numbers, and as they die their shells fall in a 



FIG. 30. 

 Globigerina living at the surface of the sea. 



gentle rain from the surface towards the sea- 

 bottom, where they frequently form a very large 

 part of the abysmal mud. 



In speaking of the organisms of the surface of 

 the sea no mention has yet been made of the 

 plant world. Of the large conspicuous Sea-weeds 



