SEA-FLOOR DEPOSITS. PART I 339 



Station WS 495. 22. xii. 29. Lat. 67 47' S. Long. 73 51' W. 2582 m. (Plate XXI.) 

 Diatomaceous mud. This is a brownish mud formed largely of flocculent material which encloses 

 diatom frustules and mineral grains. The latter are mostly below 0-05 mm. in diameter, though some 

 reach 0-2 mm. Rounded and subangular grains of quartz are most abundant, while green hornblende 

 and white mica are also noted. The chief diatom genera are Coscinodiscus and Fragilaria. Some tests 

 of Radiolaria include Sethoconus and fragments of other genera. 



Station WS 496. 30. xii. 29. Lat. 67 14' S. Long. 70 12' W. 631m. (Plate XXI.) 

 Diatomaceous mud. An unctuous green-grey mud, composed largely of diatom debris, among 

 which undamaged frustules of Cosctnodiscus, Thalassiosira, Fragilaria, Cocconeis, Corethron (often 

 with chloroplasts) and Biddulphia are plentiful. A few Radiolaria and sponge spicules are noted. 

 There is a fair proportion of mineral grains, mostly subangular in shape, up to o-i mm. in diameter, 

 including quartz, white mica and green hornblende. 



Station WS 497. 1. i. 30. Lat. 67 05' S. Long. 70 40' W. 534 m. (Plate XXI.) 

 Diatomaceous mud. A grey unctuous mud with the same general characters as the preceding 

 sample. The diatoms include Coscinodiscus, Thalassiosira, Fragilaria, Rhizosoletiia, Cocconeis and 

 Biddulphia. A few Radiolaria and rotaline Foraminifera are seen. Mineral grains reach a diameter of 

 about 0-15 mm. and include subangular fragments of quartz with some prismatic grains of green 

 hornblende. 



Station WS 498. 2-3. i. 30. Lat. 66° 21' S. Long. 69 01' W. 398 m. (Plate XXI.) 

 Sand. The mineral grains in the coarser fraction reach a diameter of about 0-5 mm. Angular 

 grains of quartz predominate over prisms of green hornblende, grains of hypersthene and fragments 

 of volcanic glass. Flocculent material is almost equal in bulk and includes diatom remains ; but only 

 frustules of Fragilaria are identified. 



Station WS 499. 3. i. 30. Lat. 65 45' S. Long. 67° 18' W. 179 m. (Plate XXI.) 

 Sand. The mineral grains range downwards in size from about 0-25 mm. in diameter. They in- 

 clude subangular grains of quartz, green hornblende and pink garnet. The fine-grained flocculent 

 material is largely diatomaceous in origin ; the chief genera are : Coscinodiscus, Fragilaria, Biddulphia, 

 Cocconeis, Thalassiosira and Corethron. 



Station WS 501. 3. i. 30. Lat. 64 52' S. Long. 63 58' W. 583 m. (Plate XXI.) 

 Diatomaceous mud. This greenish mud consists largely of flocculent aggregates formed of 

 diatoms in all stages of disintegration along with other organic debris ; the liquid also is coloured 

 green. Whole frustules of the genera Triceratium (0-5 mm. across), Coscinodiscus, Thalassiosira, 

 Fragilaria, Cocconeis, Corethron are plentiful. Mineral grains form a subordinate proportion of the 

 deposit ; they are chiefly of quartz, but occasional grains of green hornblende and possibly of chlorite 

 also occur. The grains are mainly below 0-05 mm. in diameter, but some fragments are 0-2 mm. 

 across. 



Station WS 502. 30.1.30. Lat. 69°43'S. Long. 99 38' W. 4224 m. (Plate XXI.) 



Diatomaceous mud. This sample, brown in colour, is composed mainly of flocculent material of 



the usual appearance. It contains whole frustules of Fragilaria and Coscinodiscus, together with 



fragments of Radiolaria. Mineral grains of varying size (o-2 mm. to less than o-oi mm. in diameter) 



consist chiefly of angular and rounded fragments of quartz with occasional grains of green hornblende. 



Station WS 503. 30. i. 30. Lat. 70 03$' S. Long. ioo° 39' W. 4072 m. (Plate XXI.) 

 Terrigenous mud. The sample is grey and coherent when dry. It consists largely of angular or 

 subangular mineral grains up to about 0-2 mm. in diameter. Quartz is most abundant, and some 

 grains show undulose extinction in polarized light. Fragments of green hornblende are not un- 

 common. There is some amount of flocculent material which forms aggregates enclosing mineral 

 grains, but the sample is singularly deficient in recognizable organic remains, except for a few sponge 

 spicules and frustules of Coscinodiscus which have an eroded appearance. 



