REPORT ON THE DEEP-SEA DEPOSITS. 
183 
abounding in the deposits from shallower waters near shore. The number of species of 
pelagic shells found in the deposits decreases in proportion as the colder waters of the 
polar regions are approached, till in the Globigerina Ooze of the Norwegian Sea only two 
species of pelagic Foraminifera are present. 
Everywhere a general, if fluctuating, decrease in the quantity of carbonate of lime in 
the deposits is indicated with increasing depth, till in the greatest depths of the ocean 
hardly a trace of calcareous shells can be detected in the Eed Clays or Kadiolarian Oozes, 
This absence of carbonate of lime from the deeper deposits evidently does not in any way 
depend on the conditions at the surface of the ocean, for the tow'-nets showed that the 
calcareous organisms were as abundant over the areas where none of these dead shells 
were found in the deposits as over those areas where they made up the principal part of 
the deposit in shallower depths. However, in latitudes where these shells are less 
numerous at the surface, the dead shells are removed from the deposits in lesser depths 
than in latitudes where they are more abundant. In like manner, on approaching the 
coasts, excepting always those shores which are fringed by coral reefs, a similar decrease 
in the percentage of carbonate of lime is observed, in this case, however, due to the pre- 
ponderance of land debris in terrigenous deposits. 
Glauconitic grains, glauconitic casts of the calcareous organisms, glauconitic and phos- 
phatic nodules, have been found in a large number of samples of deposits from the 
deeper water along a great many continental shores, associated with mineral particles 
derived from the disintegration of continental rocks. As in the case of the Challenger 
explorations, these materials have been found only in exceptional circumstances towards 
the central regions of the great ocean basins, as for instance where the sea is occasionally 
affected by floating ice or by winds blowing directly from desert lands. 
In the deepest water of the Indian Ocean, and in portions of the Pacific Ocean, Eadio- 
larian Ooze, Eed Clay, zeolitic and manganiferous deposits have been discovered in quite 
similar positions and conditions to those that were investigated by the Challenger 
naturalists in the Pacific, and the same may be said of Globigerina Ooze, Diatom Ooze, 
Pteropod Ooze, and the several varieties of terrigenous deposits in other regions. 
