SEA-FLOOR DEPOSITS. PART I 349 



of green hornblende are usually much smaller (0-05 mm.). The flocculent material forms dense green 

 aggregates which impart their colour to the deposit; it contains entire frustules of Coscinodisais and 

 occasional fragments of Radiolaria. 



Station WS 768. 20. x. 31. Lat. 45 31' S. Long. 63 23' W. 108 m. (Plate XVII.) 

 Diatomaceous mud. The deposit contains a considerable proportion of mineral grains. Some 

 subangular and rounded quartz grains reach 0-5 mm. in diameter, while prismatic grains of green 

 hornblende and brown volcanic glass are 0-2 mm. in length. The worn appearance of these larger 

 grains is in contrast with the fresh and angular quality of many grains between o-i and o-oi mm. 

 in diameter. Though flocculent material forms a conspicuous proportion of the deposit, recognizable 

 diatoms are not very plentiful; they include Thalassiosira, Coscmodiscus, Pleurosigma, and a chain 

 form which is not identified. A few foraminiferal tests are present. 



MARINE BIOLOGICAL STATION 



Station MS 68. 2. iii. 25. East Cumberland Bay, South Georgia; 17 miles S J° E to 8| cables 

 south-east by east of Sappho Point. 220-247 m. 



Diatomaceous mud. A fine-grained deposit, mainly debris of diatom tests, but some entire centric 

 diatoms. The mineral grains are extremely small, though some of the larger detrital grains are more 

 than o-i mm. in diameter. 



