17(5 
THE VOYAGE OF H.M.S. CHALLENGER. 
were brown or chocolate coloured, due to the presence of manganese. A glance at Dia- 
gram 16 shows the relationship between the depth and percentage of carbonate of lime. 
The surface fauna and flora was especially rich and abundant throughout. In the 
region of the Counter Equatorial Current, between the Equator and the Caroline Islands, 
pelagic Foraminifcra and ]\Iollusca were caught in great numbers in the surfaee-nets, 
surpassing in this respect an 3 hliing previously observed. This fact is most probably in 
relation with another, which ma 3 " be pointed out. In this region the soundings in 2325 
and 2450 fathoms contained respective!}" 52 and 7 per cent, of earbonate of lime, 
whereas at 2300 fathoms, in lat. 14° 44' N., only a few broken fragments of Glohigerina 
shells could be detected on microscopic examination, and at 2450 fathoms, in lat. 
19’ 24' N., there was not a trace of carbonate of lime shells in the ooze. This shows 
ajtparently that where there are numerous calcareous shells at the surface their remains 
may be found at greater depths at the bottom than where relatively less abundant 
at the surface. The pelagic Foraminifera appear to float about in great banks ; one day 
immense numbers of Pidvinulina would be taken in the net, the next day Pullenia 
would be most abundant, and Pidvinulina nearly or quite absent from the hauls. The 
heavier shelled specimens were usually taken when the nets were dragged 100 or 150 
fathoms beneath the surface. Between latitudes 10° and 20° N., Oscillatoriae were very 
numerous at the surface, and Diatoms, espeeially a large eylindrical Ethmodiscus, Castra- 
canc, were more abundant than in the tropical waters of the Atlantic far from land. 
The great abundance of Radiolaria and Diatoms is speciall}" noteworthy. 
Off Japan. — The soundings taken off the coast of Japan and in the Inland Sea (see 
Chart 35) proved to be Green and Blue ]\Iuds. Those in the Inland Sea, from depths of 
8 to 15 fathoms, were Blue Muds containing from 4 to 11 per cent, of carbonate of lime, 
consisting of a few Foraminifera, fragments of Echinoderms, Molluscs, &c. There were, 
however, no pelagic Foraminifera shells, nor were any of these organisms found in the 
surface-net gatherings during the cruise in the Inland Sea. The bulk of these deposits 
was made up of mineral matter, 40 to 50 per cent, being composed of fragments over 
O’Oo mm. in diameter, while the great mass of the fine washings consisted of finer 
mineral i)articles. IMany Diatoms were observed. 
The deposits from 345 to 775 fathoms off the coast wnre Green Muds containing from 
a trace to 5 per cent, of carbonate of lime, of which pelagic Foraminifera formed a 
considerable proportion. lUineral particles over 0’05 mm. in diameter made up from 50 
to 80 per cent., and consisted of felspars, magnetite, augite, hornblende, glauconite, 
quartz, volcanic glass, and pumice. In all these cases the mean diameter was about 
0'20 mm., while green coloured casts of the Foraminifera remained after treating a 
I'urtioii of the deposits with dilute acid. The Green ]\Iuds from Stations 236 and 236a 
might equally well be designated Blue I\Iuds, owing to the relatively small quantity 
of glauconite and the presence in some quantity of quartz fragments. 
