346 DISCOVERY REPORTS 



small dimensions. Quartz, volcanic glass and green hornblende are the chief constituents. The 

 flocculent material contains diatoms, among which Coscinodiscus is large and abundant, Actinoptychus 

 of common occurrence, while navicular forms are less plentiful. 



Station WS 663. i.vii. 31. Lat. 12 09' 36" S. Long. 77 15' W. 62 m. (Plate XXII.) 

 Diatomaceous mud. A dark green mud of similar constitution to the preceding. The minerals are 

 represented by quartz, felspar, green hornblende and volcanic glass in angular grains up to o-2 mm. 

 in diameter. There is a fair amount of flocculent material containing diatom frustules and brown 

 resting spores. The diatoms noted are Coscinodiscus (abundant), Chaetoceros, Navicula. 



Station WS 664. i.vii. 31. Lat. 12 11' 30" S. Long. 77 17' W. 100 m. (Plate XXII.) 

 Diatomaceous mud. This green mud differs from the last two samples in the greater proportion of 

 flocculent material. The presence of fragments of algal thalli containing resting spores and other cell 

 contents leaves little doubt as to the nature of the flocculent aggregates. Coscinodiscus and Actinop- 

 tychus are the principal diatoms; the former is particularly large and abundant, and many frustules 

 contain brown resting spores. Mineral grains, including quartz and green hornblende, are mostly 

 angular in shape, and occur up to 0-2 mm. in diameter. 



Station WS 665. i.vii. 31. Lat. 12 13' 18" S. Long. 77 21' 48" W. 132 m. (Plate XXII.) 

 Diatomaceous mud. The coarser fraction of this dark green mud consists of detrital material 

 grains with a maximum diameter of about 0-3 mm. ; the average size, however, is much less. Angular 

 fragments of quartz, green hornblende, felspar and volcanic glass are noted. There is a considerable 

 amount of green flocculent material which includes pieces of algal thalli and diatoms, among which 

 Coscinodiscus, Actinoptychus, Navicula and Triceratium are prominent ; some frustules contain brown 

 resting spores. Occasional textularian and rotaline Foraminifera, a radiolarian test and the silico- 

 flagellate Dictyocha fibula are noted. 



Station WS 666. i.vii. 31. Lat. 12 18' 30" S. Long. 77 30' 30" W. 198 m. (Plate XXII.) 

 Diatomaceous mud. Dark green mud of which flocculent matter is the chief constituent. This 

 green and granular aggregate contains frustules of Coscinodiscus, Actinoptychus, Cocconeis and Am- 

 phora, together with a small proportion of mineral grains. The latter are mainly angular fragments of 

 quartz, green hornblende and volcanic glass, the size of which is less than a maximum of 0-2 mm. 

 in diameter. 



Station WS 667. i.vii. 31. Lat. 12 23' 12" S. Long. 77 39' 30" W. 474 m. (Plate XXII.) 

 Sand and gravel. This sample consists of a few angular, black pebbles up to 5 mm. across, and a 

 small quantity of sand. The sand grains are mainly angular fragments of dark brown volcanic glass 

 (0-2 mm.), some shell fragments and a few grains of green hornblende. There are also some colourless 

 radial aggregates of a zeolite mineral, probably phillipsite, some of which reach a diameter of about 

 0-2 mm. 



Station WS 669. 2. vii. 31. Lat. 12 33' 30" S. Long. 78 21' 36" W. 3840 m. (Plate XXII.) 

 Diatomaceous mud. This sample consists mainly of the usual flocculent aggregates with diatoms 



and sand grains. Whole frustules of Coscinodiscus are abundant, and many contain resting spores. 



The silicoflagellate Dictyocha fibula is noted as of occasional occurrence. Mineral grains are generally 



angular and of small size, but occasional grains of quartz, green hornblende and volcanic glass reach a 



diameter of about 0-2 mm. 



Station WS 671. 3. vii. 31. Lat. 12 10' 48" S. Long. 77 59' 12" W. 1934 m. (Plate XXII.) 

 Diatomaceous mud. The main constituent is granular flocculent material containing brown resting 

 spores and diatoms. The most prominent genera are Coscinodiscus (large and abundant), Triceratium, 

 Actinoptychus, Synedra and Navicula. Occasional Radiolaria (Eucyrtidium and Lithostrobus) and the 

 silicoflagellate Dictyocha fibula are noted. Mineral grains, sparsely distributed in the deposit, include 

 quartz, green hornblende and volcanic glass, in grains up to o-i mm. in diameter. 



