576 T. C. CHAMBERLIN 
activity. There is no free supply of any competent discharging 
agency independent of sea life. 
Variations of lime-secretion by sea life-—The amount of lime- 
secreting sea life is greatly influenced by the temperature of the 
sea and by favorable habitat. Lime-secreting sea life, both 
plant and animal, is greatly favored by high temperature and 
reduced by low. In support of this the following statements 
from the Challenger Report’ and other sources may be offered, 
in which I have italicized the significant parts : 
Species of algae which secrete carbonate of lime are abundant in the 
shallow waters of the ocean. In the ¢vopical regions especially there are 
massive species of Lzthothamnion, Lithophyllum, Halimeda and other genera 
that make up a large part of some coral reefs and of the surrounding coral 
sands and muds. Zwo hundred fathoms is probably the extreme limit at 
which any of these organisms live in the ocean. 
Rhabdospheres are especially developed in eguatorial and tropicac 
regions, and are rarely met with in regions where the temperature of the 
surface water falls below 65° F. (18.3° C.). Coccospheres, while abundant 
in tropical waters, are found further north and south than the Rhabdospheres ; 
they are present even where the temperature on the surface is as fow as 45° 
F., (7.2 C.); indeed, Coccospheres attain their greatest development in Zem- 
berate regions. These organisms are absent or vave in coast waters affected 
by rivers; they especially flourish in the pelagic currents of the open ocean. 
. In Arctic and Antarctic waters Coccospheres and Rhabdospheres are 
replaced by similar minute alge whzch do not, however, secrete rods and 
disks of carbonate of lime on thetr outer surfaces. 
Rhabdoliths and Coccoliths—the broken down parts of Rhabdospheres 
and Coccospheres— play a most important part in all deep-sea deposits, wzth 
the exception of those laid down in polar and subpolar regions. 
Of all the organic remains met with in marine deposits, by far the most 
frequent are the shells of Foraminifera, it may be safely said that these 
organisms or their fragments are present in every average sample of marine 
mud, clay, ooze or sand. ... Wearly all the spectes are confined to tropicas 
and subtropical waters, they gradually disappear from the surface-nets as 
the polar regions are approached, the dwarfed forms Globigerina pachyderma 
and Globigerina dutertret, being the only species met with in Arctic and 
Antarctic waters. . .'. Jz the calcareous oozes from tropical regions, the shells 
of all the spectes inhabiting the surface waters are observed in enormous 
abundance, but these same spectes are never met with in deposits from polar 
TE ZLOMS artis» 
* Challenger Report, Deep Sea Deposits, pp. 257, 258-261, 263, 31 and 266. 
