1897] DISTRIBUTION OF PELAGIC FORAMINIFERA 23 
more abundant than adult ones, still shells as heavy as any in the 
deposits are occasionally taken in the surface-nets. The young 
individuals are likewise more abundant at the surface than in the 
deposit, when compared with the adult shells present ; this is 
especially the case in deposits from very deep water. This arises, 
as we shall see, from the more rapid solution of the young shells as 
they fall through the sea-water to the bottom. 
When examining a deep-sea deposit it is always possible to say, 
from a study of the pelagic shells of the Foraminifera, whether the 
sample comes from the tropics, the temperate or the polar regions, 
but from the examination of these shells alone it would be extremely 
diffteult to say whether the specimen was from the northern or 
southern hemisphere. 
Off the Agulhas Bank at the Cape of Good Hope, off the east 
coasts of Australia and Japan, and off the east coasts of North and 
South America, oceanic currents from different sources meet and 
Fic. 4.—Pulvinulina menardii (d’Orbigny), from the tropical deposits. 
mix, and there is a wide range of annual temperature at the sur- 
face. In these positions large numbers of pelagic Foraminifera (as 
well as other organisms) appear to be killed by the sudden changes 
of temperature, and consequently there are indications that the 
deposits, so far as due to these shells, are accumulating more rapidly 
in these, areas than in other situations. It is a curious fact also 
that in these regions the deposits of glauconite and phosphatic 
nodules are more abundant than elsewhere. 
In a certain sense the course of a surface oceanic current can 
be traced on the bottom by means of these dead pelagic shells ; 
for instance, the axis of the Gulf Stream is marked out by deposits 
of Globigerina Ooze from the Strait of Florida to within the Arctic 
circle. No similar warm current enters the Antarctic region, and 
consequently no true Globigerina Ooze is found to the south of 
lat. 50°S. When the Challenger took her first deep-sea sound- 
ing after leaving Heard Island (in lat. 60°S.) there was much 
speculation as to what the nature of the deposit would be. I 
