•258 
THE VOYAGE OF H.M.S. CHALLENGER. 
of the open ocean ; they are usually found entangled in the gelatinous matter of the 
Radiolarians, Diatoms, and Foraminifera, and are seldom absent from the stomachs of 
Salpie, Pteropods, and other pelagic animals. 
Rhabdoliths and Coccoliths — the broken-down parts of Rhabdospheres and Cocco- 
Fic, 20.— A Rhalxlosphere. From the surface 
Fig, 21. — A Khabdosphere. From the surface 
spheres — play a most important part in all deep-sea deposits, with the exception of 
those laid down in polar and subpolar regions. In terrigenous deposits they are much 
less abundant than in pelagic deposits ; in some Blue Muds and other terrigenous deposits 
they are either rare or absent, while in all Globigerina and Pteropod Oozes they make 
up a large portion of the carbonate of lime in the deposit. Perfect Rhabdospheres are 
never found in the deposits ; they are very easily broken up into Rhabdoliths, which are 
at times very abundant. Coccospheres are found in considerable numbers in deposits 
from the temperate regions in all moderate depths, but they are rare in the deposits from 
tropical regions, where the spheres, from not being so compact, break up more readily 
into Coccoliths (Cyatholiths), and they are generally, like other calcareous remains, absent 
from Red Clays and Radiolarian Oozes. 
Tlie general appearance of these minute fragments under the microscope, when 
the finer parts of a Globigerina Ooze are examined, is represented on Plate XI., fig. 
U, showing Rhabdoliths and Coccoliths from Station 338, lat. 21° 15' S., in 1990 
fathoms, fig. 4 Coccospheres and Coccoliths from Station 166, lat. 38° 50' S., in 275 
fathoms. 
Foraminifera . — Of all the organic remains met with in marine deposits by far the most 
