CRUSTACEA OF THE DEEP SEA 119 



is covered with a soft grey ooze, made up almost 

 entirely of the dead shells of Foraminifera rained 

 down from above. Since the commonest species 

 of Foraminifera found under these circumstances 

 belong to the genus Globigcrina, the deposit is 

 known as " Globigerina ooze." 



In certain regions of the ocean the shells of other 

 floating organisms largely replace those of the 

 Foraminifera in covering the ocean floor, and in 

 the deepest abysses so deep that the shells of 

 surface animals are dissolved before they can sink 

 to the bottom there is found a deposit known as 

 the " red clay," which appears to be derived largely 

 from the impalpable volcanic and cosmic dust that 

 floats in the atmosphere. It is not necessary for 

 our present purpose to enter more fully into the 

 interesting questions connected with these deep-sea 

 deposits, but it is important to remember that, 

 generally speaking, the floor of the deep sea is 

 everywhere soft ooze, without rocks or stones, 

 except for an occasional water-logged lump of pumice 

 or a stone dropped by a melting iceberg. This fact 

 is probably of great importance in the life of deep- 

 sea animals. 



One of the most peculiar and characteristic of the 

 physical conditions in the deep sea is the enormous 

 pressure under which life has to be carried on. At 

 the surface of the sea the pressure of the atmosphere 

 is, roughly speaking, 14^ pounds per square inch. 



