EEPORT ON THE DEEP-SEA DEPOSITS. 
193 
may be added a few bottom-living Foraminifera, such as Miliolina, Textularia, and 
others, with remains of Echinoderms, Molluscs, and a few teeth of fish and Cephalopod 
beaks. It is very seldom, if indeed it ever happens, that the shells of Pteropods, 
Heteropods, and Coccospheres are found in a characteristic Red Clay from the deep sea. 
In the above 70 samples Globigerinidae are represented in 43 cases, bottom-living Fora- 
minifera (Miliolidse, Textularidse, Lagenidse, Rotalidse, Nummulinidse) in 34 cases, teeth 
of fish in 34 cases, Echinoderm fragments in 22 cases, Ostracodes in 10 cases; Lamelli- 
branchs, Gasteropods, Brachiopods, otoliths of fish, Polyzoa, Cephalopod beaks, and bone 
fragments are more sparingly represented, while remains of Pteropods, Coccospheres, 
Coccoliths, and Rhabdoliths occur in a few exceptional cases. 
The carbonate of lime in these Red Clays ranges from 0 in 13 cases, and traces in 21 
cases, to 28‘88 per cent, at Station 30, in 2600 fathoms — the average percentage of car- 
bonate of lime in these 70 samples being 6 ‘70 per cent. The relation of the carbonate 
of lime to depth is shown thus — 
18 samples from 2000 to 2500 fathoms contain on the average 8‘39 per cent. CaCOg 
42 „ 2500 to 3000 „ „ 716 
7 „ 3000 to 3500 „ „ 0 88 
3 „ over 3500 „ „ 2'38 „ „ 
One doubtful sample from 3875 fathoms, where there was almost certainly an ad- 
mixture of carbonate of lime from another station, causes the rise in the last subdivision 
over 3500 fathoms; otherwise the carbonate of lime would be represented merely by 
traces at these depths. 
The remains of pelagic organisms with siliceous shells, skeletons, and frustules, are 
widely distributed in the Red Clay areas, though occasionally they would appear to be 
entirely absent from the deposits of these regions. When the Radiolarian remains 
increase in number so as to form a very considerable portion of the deposit, as in some 
tropical areas of the Pacific and Indian Oceans, the Red Clay passes into Radiolarian 
Ooze ; when the Diatom remains in like manner increase, as in the Southern Ocean, the 
Red Clay passes into a Diatom Ooze, and in other regions into a Globigerina Ooze, or 
Blue Mud. The siliceous spicules of Sponges are found sometimes sparingly, some- 
times in considerable abundance, in nearly all samples of Red Clay. 
The mean percentage of siliceous organisms is 2 ‘39. Radiolaria were observed to be 
present in 61 cases. Sponge spicules in 49 cases. Diatoms in 32 cases, arenaceous 
Foraiminifera (Astrorhizidse, Lituolidse, Textularidse) in 49 cases, and glauconitic casts of 
calcareous organisms in 2 cases. 
According to the Challenger researches, life appears to be universally distributed over 
the floor of the ocean, but to be much less abundant on the red clay areas than on any of 
the other kinds of Marine Deposits, and apparently to reach its zero in the greatest depths 
(deep-sea deposits chall. exp. — 1890.) 25 
