SEA-FLOOR DEPOSITS. PART I 345 



Station WS 647. 22. vi. 31. Lat. 15 19' 12" S. Long. 75 11' 30" W. 65 m. (Plate XXII.) 

 Fine sand. The sample consists almost entirely of detrital mineral grains, but there is a small 

 amount of flocculent material which, however, is sufficient to impart a greenish tinge to the sand. 

 The grains are mainly angular and include quartz (0-25 mm.), plagioclase felspar (0-2 mm.), green 

 hornblende (o- 1 mm.) and volcanic glass (0-2 mm.). Among diatoms, large frustules of Coscinodiscus are 

 abundant and some contain brown resting spores. Actinoptychus commonly occurs, while Navicula, 

 Synedra, Grammotophora, Achnanihes, Pleurosigma and Entopyla are less numerous. Sponge spicules 

 and Foraminifera (cristellarians and textularians) are also present in the deposit. 



Station WS 648. 22. vi. 31. Lat. 15° 19' 30" S. Long. 75° 13' W. mm. (Plate XXII.) 

 Diatomaceous mud. A green mud, consisting mainly of flocculent diatomaceous material with 

 only a small proportion of detrital mineral grains. The latter are chiefly angular grains of quartz and 

 green hornblende which do not average more than 0-05 mm. in diameter. Though diatoms are 

 plentiful, the variety of forms is not great. The largest and most abundant frustules are those of 

 Coscinodiscus, many of which reach a diameter of nearly 0-5 mm. ; some have greenish cell contents, 

 others contain brown resting spores. Other forms which are occasionally seen are Actinoptychus, 

 Achnanihes and Grammatophora. Brown resting spores also occur loose in the green flocculent 

 material. 



Station WS 649. 22. vi. 31. Lat. i 5 2o'S. Long. 75 16' 30" W. 137 m. (Plate XXII.) 

 Diatomaceous mud. This sample differs from the preceding chiefly in the greater maximum size 

 of the sand grains; in the present sample some angular quartz grains are 0-2 mm. across, and prisms 

 of green hornblende are nearly as long. But the mineral constituent is relatively smaller in amount 

 than the flocculent matter which is closely similar to that from St. WS 648. There is also the same 

 preponderance of large frustules of Coscinodiscus, and the associated diatoms include Actinoptychus, 

 Achnanthes and Navicula. 



Station WS 650. 22. vi. 31. Lat. 15 22' 30" S. Long. 75 22' W. 143 m. (Plate XXII.) 

 Coarse sand. The major fraction consists of colourless and opaque sand grains, more or less rounded 

 in shape, up to 2 mm. in diameter. They are often coated with green flocculent matter. In the finer 

 material a large species of Coscinodiscus commonly occurs with textularian and rotaline Foraminifera. 

 The granular flocculent material also encloses abundant crystals of phillipsite. 



Station WS 651. 22. vi. 31. Lat. i 5 3 i'S. Long. 75 37' 30" W. 1264 m. (Plate XXII.) 

 Diatomaceous mud. This deposit is composed mainly of green flocculent matter in which 

 broken tests of diatoms, and brown resting spores are abundant. A large species of Coscinodiscus 

 occurs plentifully, while frustules of Entopyla, Achnanthes and Actinoptychus are less numerous. 

 Some of the frustules enclose brown resting spores. The sand grains embedded in the flocculent 

 mass are mostly less than 0-05 m. in diameter, though some reach o-i mm. Angular grains of quartz 

 and prismatic grains of green hornblende represent the chief minerals. 



Station WS 652. 23. vi. 31. Lat. 16 21' 30" S. Long. 76 30' 12" W. 3840 m. (Plate XXII.) 

 Diatomaceous mud. An unctuous grey-brown mud composed almost entirely of flocculent 

 matter, in which diatom frustules occur in all stages of disintegration. Coscinodiscus is represented 

 in abundance by unbroken frustules, and Radiolaria are present in small numbers. The minor 

 proportion of mineral grains includes quartz and green hornblende in fragments which are usually 

 less than 0-05 mm. in diameter. 



Station WS 655. 24. vi. 31. Lat. i6°o8'S. Long. 76 22' W. 3315 m. (Plate XXII.) 

 Diatomaceous mud. This brown mud is so similar to the preceding that the same description 

 applies. 



Station WS 658. 25. vi. 31. Lat. 13 45' 30" S. Long. 76 20' W. 16 m. (Plate XXII.) 

 Diatomaceous mud. A dark green, rather sandy, mud of which the greater proportion consists of 

 mineral grains, mostly angular in form and ranging from a diameter of about 025 mm. to exceedingly 



