SEA-FLOOR DEPOSITS. PART I 317 



Station 74. 3. vi. 26. Lat. 40 31' 40" S. Long. 38 14' 50" W. 5446 m. (Plate XVII.) Three 

 samples: upper 3 cm., middle 3 cm., and bottom 3 cm., from a core 24 cm. in length. 



Radiolarian ooze. An unctuous brown mud, mainly composed of extremely small particles 

 which together form a flocculent mass. This contains some centric and navicular diatoms, sponge 

 spicules and, more abundantly, Radiolaria. Tests of the latter group are plentiful in coarser washings 

 from the top section of the sample. They are mainly spheroid and discoid forms, such as Ceno- 

 sphaera, Hexastylus, Carposp/iaera, Heliodiscus, Porodiscus, and Rhopalastrtem. Nasselarian forms are 

 rare and small in size. Radiolaria are not abundant in the meagre washings yielded by the middle 

 and lower sections of the sample. 



Mineral grains are common in the upper section, with diameters up to about o-i mm. They are 

 mainly angular grains of quartz, but some coloured minerals occur also. On the whole, mineral 

 grains appear to decrease in quantity downwards in the core. 



Station 77. 6. vi. 26. Lat. 39 19' 30" S. Long. 35 27' 40" W. 5186 m. (Plate XVII.) 



Radiolarian ooze. The sample consists of a core 47 cm. long. In general constitution the sample 

 is a brown mud which becomes pale on drying. A considerable part of the deposit is composed of 

 flocculent material ; this consists of extremely small particles most of which appear to be isotropic 

 in polarized light, though others are certainly anisotropic. Mingled with this material are mineral 

 grains, Radiolaria and a few other organic remains (such as diatoms), which vary proportionately in 

 different parts of the core. 



The top part of the core is extremely rich in Radiolaria, which show a great variety of form. 

 Speaking generally, the spumellarian forms are abundant, but nasselarians are comparatively rare in 

 the residue examined. Of the spumellarians, the spheroid genera Cenosphaera, Carposphaera, and 

 Hexastylus, and the discoid genera Heliodiscus and Porodiscus are specially abundant and well de- 

 veloped, while Rhopalastrum and Hymeniastrum are both rare and smaller. Among the few nasse- 

 larians, the genera Sethopyramis, Lychnocanium and Clathrocyclas are noted. Only a few small 

 angular mineral grains appear in the residue. 



The middle section yields a much smaller residue consisting mainly of Radiolaria. The spheroid 

 and discoid genera are predominant, and similar to those mentioned above; likewise, nasselarian 

 forms are rare. 



The lower section contains a larger proportion of mineral grains, which vary in diameter up to 

 o-i mm., but some are even larger. Radiolaria are present, especially spheroid and discoid forms, 

 but they are less plentiful than in the higher sections of the core. 



Station 78. 12. vi. 26. Lat. 35 18' S. Long. 19 01' 10" W. 3410 m. (Plate XVII.) 

 Globigerina ooze consisting mainly of extremely fine particles, many of which react to polarized 

 light; among these, coccoliths and rhabdoliths are plentiful. Large tests (up to 0-5 mm.) of Globi- 

 gerina occur, but no mineral grains were seen. 



Station 83. 21. vi. 26. Lat. 32 31' 50" S. Long. i° 23' 30" W. 4308 m. (Plate XVII.) 

 Globigerina ooze. A pale ooze formed mainly of comminuted Globigerina tests, but some whole 



shells reach 0-5 mm. in diameter. Some broken echinid spines occur, but no mineral grains are noted. 



Coccoliths and rhabdoliths occur plentifully in the finer fraction. 



Station 84. 22. vi. 26. Lat. 32 52' S. Long. i° 55' E. 2233 m. (Plate XVII.) 

 Globigerina ooze. Large tests of Globigerina with much comminuted material, coccoliths and 

 rhabdoliths in the finer fraction. No mineral grains were seen. 



Station 89. 28. vi. 26. Lat. 34 05' 15" S. Long. 16 00' 45" E. 3926 m. (Plate XVII, inset.) 



Globigerina ooze. The sample consists of a core, 30 cm. long. The deposit is closely similar to 



the samples from Sts. 83 and 84, but there is a slight proportion of small mineral grains (up to 



0-05 mm. diameter). Otherwise, there are the usual Globigerina tests up to 0-2 mm. across and a 



considerable proportion of fine material in which coccoliths, rhabdoliths, sponge spicules and 



