78 THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 



D. BLUE MUD. The samples of Blue Mud were all of a greenish color, 

 except one which had undergone decomposition in the bottle, and had turned 

 black with a thin layer of a gray color on the top. The percentage of cal- 

 cium carbonate varied from to about 5, while one sample, apparently ap- 

 proaching the border-line of Globigerina Ooze, gave on analysis 15.15 per cent. 

 The siliceous organisms ranged from 1 to 5 per cent, principally Diatoms, 

 with Sponge spicules, Radiolaria, and arenaceous Foraminifera. In one 

 sample the Diatoms were impregnated with sulphide of iron in the form of 

 minute spherules. The minerals made up from 10 to 40 per cent, the 

 quartz grains in one sample attaining a diameter of 0.6 mm., and in another 

 0.4 mm. ; besides quartz, mica, felspar, and hornblende were noted. One 

 sample contained rock fragments ranging up to 3 inches in diameter, a 

 rolled pebble, worm-eaten twigs, worm-tubes [Oniiphis, one very large), 

 fragments of bone, and hardened blocks of deposit, associated with a little 

 of the mud in which the other items enumerated were apparently embedded. 



E. GREEN SAND. The four samples of Green Sand may possibly have all 

 come from the same station. Though the percentage of calcium carbonate 

 seemed to vary somewhat (one sample analyzed gave 13.24 per cent, while 

 another seemed to contain about 25 per cent), one-half of the individual 

 samples was apparently made up of glauconite grains and glauconitic casts, 

 representing, indeed, one of the purest green sands ever submitted to us 

 for examination. Quartz and mica, and a few siliceous organisms (Sponge 

 spicules, Diatoms, and Radiolaria) were also noted. 



F. GREEN MUD. The sample of Green Mud has undergone decomposition 

 in the bottle, for the lower portion is much darker green than the upper 

 portion. Analysis gave 61.63 per cent of calcium carbonate, made up 

 principally of pelagic and bottom-living Foraminifera, while many Radio- 

 laria, with a few Diatoms and Sponge spicules, were noted, in addition to 

 glauconitic. casts and glauconite grains and other minerals. 



G. VOLCANIC MUD. The sample, though containing about 20 per 

 cent of calcium carbonate (pelagic Foraminifera with coccoliths and many 

 rhabdoliths), is principally made up of volcanic material, the particles col- 

 ored black, brown, and yellow, and having the appearance of volcanic ash. 



H. INCOHERENT MATERIAL. One sample consists principally of manga- 

 nese nodules, embedded in a deposit that might be called a Radiolarian ooze. 



