591.9/9 17 



593.12 



I. 



On the Distribution of the Pelagic Foraminifera at 

 the Surface and on the Floor of the Ocean. 



THE pelagic Foraminifera play a most important role in the 

 economy of the present ocean, as well as in the geological 

 history of our planet. Living specimens of these pelagic Protozoa 

 are distributed everywhere in the surface waters of the open ocean, 

 about fifteen or twenty species being met with in the surface waters 

 of the tropics, and one or two dwarfed species are captured among 

 the floating icebergs of the Arctic and Antarctic regions. The dead 

 shells of these Foraminifera make up by far the larger part of the 

 carbonate of linie present in the deep-sea deposits known as Pteropod 

 and Globigerina Oozes, which cover about 50,000,000 square miles 

 of the ocean's bed. In addition, they make up the major part of 

 the carbonate of lime present in the other deep-sea deposits, such as 

 Diatom Ooze, Eadiolarian Ooze, Eed Clay, and the deeper terrigenous 

 deposits which are laid down in close proximity to continents and 

 oceanic islands. Indeed, it may be said that, taken as a whole, 

 nine-tenths of the carbonate of lime in marine deposits from depths 

 greater than one hundred fathoms is derived from the dead shells of 

 the pelagic Foraminifera. 



When the Challenger set out on her cruise around the world, 

 all the naturalists of the expedition believed that the habitat of the 

 Glohigcrinae was on the sea-bed in deep water. This opinion was 

 held by Wallich, 1 Carpenter, 2 and Wyville Thomson. 3 Gwyn 

 Jeffreys, 4 however, took another view ; he regarded the Globigcrinae 

 as surface organisms, and the Globigerina Ooze as made up of dead 

 shells which had fallen to the bottom from the surface waters. The 

 fact that M'Donald 5 and Major Owen 6 had captured several species 

 of these Foraminifera in tow-nets at the sea-surface appears to have 



1 The North Atlantic Sea-bed. London, 1862; also Deep-Sea Researches on the 

 Biology of Globigerina. London, 1876. 



2 Proc. Roy. Soc, vol. xxiii. p. 234. 1875. 



3 Proc. Roy. Soc, vol. xxiii. p. 32. 1874. 



4 Proc. Roy. Soc, vol. xviii. p. 443. 1869. 



5 See Huxley's Appendix to Dayman's Report on Deep-Sea Soundings in the North 

 Atlantic made in H. M.S. Cyclops in June and July 1857. London, published by the 

 Admiralty, 1858. 



6 Journ. Linn. Soc LoncL, vol. ix. (Zool.), p. 147. 1866. 



B 



