THE DEPOSITS OF THE SEA-BOTTOM. 63 



particles 0-05 — 0'02 ram may be divided. The lighter ingredients are commonly of a brown or brown- 

 gray colour, while the heavier ones are black-gray. 



The finest ingredients, under o-02 ram , are of very small interest; they consist of clay and small, 

 indeterminable grains of minerals; besides they often contain Diatoms and pieces of Radiolaria 

 and sponge spicules. The colour is that of the specimen itself, it being determined by the clayey 

 ingredients. 



