THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 79 

 It contains no calcium carbonate, and besides the siliceous organisms and 

 manganese grains, only a few minerals were observed in the clayey matter. 

 Another sample consists of: (1) a small piece of volcanic rock in process 

 of transformation into palagonite, (2) a flat piece of palagonite much im- 

 pregnated with manganese, and (3) a small manganese nodule. 



