526 Mr. J. Murray on Oceanic Deposits examined 



Our deepest sounding (4475 fathoms or 4575, see p. 504) was a Eadio- 

 larian ooze ; with, the exception of a little amorphous matter, manganese 

 particles, a few yellow cherty-like particles, and some pumice pieces, this 

 bottom was entirely composed of the exuviae of organisms with siliceous 

 skeletons — as Eadiolaria, one or two Diatoms, and some organisms which 

 seem to be undescribed (Challengerias), but which are numerous in the 

 deeper waters of the Pacific (see notes on surface animals, p. 536 J. 



A section of about 3 inches came up. The upper two were of a red 

 colour, due to the presence of much manganese ; the lower one was a 

 pale straw-colour, and contained relatively few manganese grains. 



In our trip from the Sandwich Islands to the Society Islands we again 

 met with Eadiolarian ooze. Between 7° and 12° north of the equator we 

 came on a patch represented by four soundings, some of these containing 

 not a single Globigerina ; then just on the equator, in two soundings, one 

 at a depth of 2925 fathoms, we got a Globigerina-ooze containing a good 

 many Eadiolaria. Between 2° and 10° south we again had a patch of 

 Eadiolarian ooze represented by three soundings, and containing only a 

 few pelagic Foraminifera or their broken parts. The occurrence of this 

 patch of Globigerina-oozQ in the position indicated (see map, Plate 20), 

 and the comparative or total absence of the Globigerina-shells in the 

 deposits a little to the north and south of it, is sufficiently curious and 

 significant. It will be well to note that, in the Globigerina-])a,tch, man- 

 ganese and other mineral particles are much less abundant than in the 

 adjacent Eadiolarian. Note also the presence of the south equatorial 

 current and the dip of some isotherms over the Globigerina-^&tck. One 

 or two soundings to the east of Japan might have been classed under 

 this head ; but in them the siliceous remains do not make up over one 

 third of the sample in bulk. Generally it may be said that in the 

 "Western and Middle Pacific the siliceous remains of Eadiolaria and Dia- 

 toms are abundant in the deposits, whereas in the South Pacific and 

 Atlantic they are much less so, or absent in the bottoms. 



The following are the depths of the soundings placed under the head 

 of Eadiolarian ooze : — 



fms. fms. fms. 



f 4575 2700 2600 



t 4475 2900 2350 



2750 2250 2750 



4. Diatomaceous Ooze. — South of the latitude of the Crozets, on our 

 southern trip, we found Diatoms abundant, both in the surface-waters 

 and in the bottom. 



About the Crozets, Kergueien, M'Donald's Islands, and close to the 

 ice-barrier, the frustules of these organisms were very abundant in the 

 soundings, but were masked by much land-debris. Between the parallels 

 of 53° and 63° S., i. e. between the north edge of the ice and the latitude 

 of M'Donald's Islands, we got in three soundings a pale straw-coloured 



