SEA-FLOOR.DEPOSITS. PARTI 319 



sponge spicules and occasional mineral grains, while coccoliths and rhabdoliths occur in the finer 

 material. 



Station 102. 28. x. 26. Lat. 35 29' 20" S. Long. 1 8° 33' 40" E. 1800 m. (Plate XVII, inset.) 

 Globigerina ooze. A grey mud, rather pale when dry. The deposit consists mainly of minute 

 particles (including coccoliths) which form flocculent patches on the glass slip. Foraminiferal shells 

 are fairly abundant, mostly those of Globigerina. Sponge spicules also occur. There is a fair propor- 

 tion of mineral grains, mostly rounded or subangular, up to o-i mm. in diameter. While most of the 

 mineral grains are colourless, some rounded green grains, which show aggregate polarization, may 

 be glauconite. Though classified as a Globigerina ooze, this deposit is not typical of that group ; the 

 proportion of mineral grains is too high and that of Foraminifera is correspondingly small. The 

 station is situated on the margin of a region marked by the occurrence of glauconitic deposits. 



Station 117. 17. xi. 26. Lat. 52 20' 40" S. Long. 3 48' 45" E. 1723 m. (Plate XVII.) 



Diatomaceous mud. A small sample, brownish grey when wet, from "about 5 miles N 72 E of 

 Bouvet Island ". The deposit consists mainly of diatom tests, among which Coscinodiscus, Fragilaria 

 and Thalassiothrix are most abundant, the first named attaining a diameter of 0-25 mm. There is a 

 fair quantity of mineral grains, chiefly angular and rounded quartz grains up to 0-2 mm. in diameter ; 

 prismatic fragments of green hornblende, up to 0-25 mm. in length, are also present. The proportion 

 of mineral material determines the classification of this deposit as diatomaceous mud rather than 

 diatom ooze. 



Station 123. 15. xii. 26. Off mouth of Cumberland Bay, South Georgia. From 4-1 miles N54°E 

 of Larsen Point to 1-2 miles S 62 W of Merton Rock. 250 m. (Plate XIX, inset.) 



Diatomaceous mud. An extremely fine-grained mud, with entire tests of centric and navicular 

 diatoms, the diameter of which is mainly below o-i mm. The fine material seems to consist in great 

 part of comminuted diatoms. Quartz grains are present in fair quantity, but are mainly less than 

 0-05 mm. in diameter; the occasional grains of green hornblende are also small. 



Station 129. 19. xii. 26. Lat. 53 28' 30" S. Long. 37 08' W. 1001 m. (Plate XIX.) 

 Diatomaceous mud. A very small sample which has settled out into black and light-coloured 

 layers, representing the approximate separation of detrital and organic constituents. The organic 

 material contains centric and navicular diatoms, the former reaching a diameter of 0-2 mm. Elongate 

 diatoms and sponge spicules are present in some abundance and occasional Radiolaria are noted. 

 Much light flocculent material consists entirely of fragmentary diatom tests. Mineral grains, reaching 

 a diameter of o-i mm., are present in fair quantity. They are mostly rounded and subangular frag- 

 ments of quartz, but blue-green prismatic grains of hornblende and some opaque grains occur. 

 No stones are present in the sample, though these are recorded in the Station List. 



Station 131. 20. xii. 26. Lat. 53 59' 30" S. Long. 36 11' W. 240 m. (Plate XIX, inset.) 

 Diatomaceous mud. The material consists largely of diatoms in some variety, among which 

 Fragilaria and Coscinodiscus are predominant, the latter reaching 0-2 mm. in diameter. Sponge 

 spicules are also present. There is some quantity of mineral grains which rarely attain o-i mm. in 

 diameter; they are mainly rounded colourless quartz fragments, but prismatic green hornblende is 

 noted. Stones are recorded in the Station List but there are none in the sample. 

 Station 136. 21. xii. 26. Lat. 54 22' S. Long. 35 21' W. 246 m. (Plate XIX.) 

 Glauconitic mud. The sample is a light grey mud when dry, but is greenish when wet. No 

 stones are present. The bulk of the material consists of mineral grains reaching a diameter of o-2inm., 

 though the average size is much less. There is probably a fair variety of minerals, among which 

 green hornblende is conspicuous, but the large majority of grains are subangular fragments of quartz. 

 Deep green glauconite is present, sometimes filling the canals of sponge spicules. The finer material 

 includes diatom frustules, mainly fragmentary, but whole tests of Coscinodiscus and Fragilaria are 

 present. The apparent absence of calcareous tests is noteworthy, in view of their constant association 

 with glauconite elsewhere. 



