16 THE DEPTH AND MARINE DEPOSITS OF THE PACIFIC OCEAN. 
dant on the bottom, as well as in the mud of the manganese nodules, though 
among the nodules it was not uncommon to find an occasional Bioculina. 
Many of the dead radiolarians found on the bottom were obtained from the 
guts of Salpse swimming near the surface or within the 300-fathom line in 
the tow-nets sent to that depth. The same is the case with many of the 
Dinoflagellata which lave beén considered as deep-sea types. . . . 
“The samples of the bottom obtained by the soundings taken by the 
expedition or gathered in the mud-bag and in the trawl indicate that an 
immense area of the bottom of the Eastern Pacific is covered-with manga- 
nese nodules, and that they play an important part in determining the 
character of the bottom, not only in the area covered by this expedition but 
also in other oceanic regions ; the Eastern Pacific area of manganese nodules 
probably extends to the northwest of our lines to join the stations where 
manganese nodules were found by the ‘ Albatross’ in 1899 in the Moser 
Basin, on the line, San Francisco to Marquesas (PI. 3). 
“This area may also extend south of our lines, Callao to Easter Island, 
and join the line west of Valparaiso where the ‘Challenger’ obtained man- 
ganese nodules at many stations. I do not mean to imply that manganese 
nodules are present to the exclusion of radiolarians and of globigerinz. It 
is probable that the layer of nodules is partly covered by them, and by the 
thick, sticky, dark chocolate-colored mud which is found wherever manganese 
nodules occur. . . . 
“The Salpx guts gave us, in addition to the finer tow-nets, immense col- 
lections of radiolarians, diatoms, and dinoflagellata, many of which have 
been considered to live at great depth and upon the bottom. It is most 
interesting to note the number of diatoms found in this tropical region. 
They have usually been considered as characteristic of more temperate and 
colder regions. On several occasions the surface waters were greatly dis- 
colored by their presence, and the extent of their influence on the bottom 
deposits is shown by the discovery of a number of localities where the 
bottom samples at depths from 1490 to 2845 fathoms, in the track of the 
great Peruvian current, formed a true infusorial earth.” 
After these interesting extracts, giving details of the observations made 
on board ship during the various cruises, we may now proceed to a detailed 
description of the samples of these deposits which were sent to us for 
examination. 
