78 EXPEDITION OF THE “ALBATROSS,” 1899-1900. 
The same may probably be said of the Radiolarians. ‘The surface Radiolarians are 
less numerous than the species living near the bottom, but the pelagic species occur 
in such hosts as to outweigh at certain localities those living on the bottom. The 
number of pelagic species of Radiolarians* is far greater than that of the Globigerina, 
and there are no groups of the former living attached to the bottom, as in the case with 
the arenaceous and porcellanous types of Foraminifera, On the other hand there must 
be living and floating in close proximity to the bottom, far from continents and at depths 
greater than 2000 fathoms, hosts of abyssal Radiolarians, among which the Nasselaria 
and the Pheodaria predominate. As a general rule the abyssal forms are characterized 
by their smaller size and massive skeletons, while the surface types are distinguished 
by their more delicate skeletons.? The surface and pelagic Radiolarians probably do not 
extend far beyond 200 fathoms in depth, and belong especially to the Spumellaria and 
Acantharia, and, according to Haeckel, with but few Osculosa, and fewer Pheodaria than 
Nassellaria. Unfortunately, no detailed account of the bathymetrical range of the 
minor groups of Radiolarians accompanies the report of Haeckel, but he naturally 
attaches the greatest significance to the dependence of their geographical distribution 
on oceanic currents. 
The bottom deposit at the stations in the vicinity of the Marquesas are 
characterized by an admixture of Globigerina ooze and volcanic particles, 
In the channel separating the Marquesas from the northwestern Pau- 
motus, a distance of not more than 450 miles, the deeper parts, in from 2456 
fathoms to 2700 fathoms, are marked by all the characteristics of the 
deposits in the deeper parts of the eastern Pacific north of the Marquesas ; 
the deposits passing from red clay associated with Radiolarians to red clay 
mixed with Foraminifera, and in the lesser depths, 1208 fathoms to 1932 
fathoms, we meet with deposits consisting of Globigerina ooze, and finally 
coral sand in the vicinity of the Paumotu Plateau. 
Again in the channel separating the Paumotus from the Society Islands 
a deposit allied to red clay, composed in part of Globigerina, was found 
in the deeper parts at a depth of somewhat over 2200 fathoms; the Glo- 
bigerinsee becoming mixed with large proportions of volcanic mud as we 
approached the Society Islands. 
1 Haeckel enumerates more than 4300 species, and remarks that probably twice that number 
could be distinguished from a more detailed examination of the “Challenger” material. Report 
on the Radiolaria collected by H. M. S. “Challenger,” 1887.  Zodlogy; Vol. XVIII., First 
Part, p. is 
2 Haeckel, 1. ¢., p. clfi. 
8 Haeckel, l.c., p. exlvi. 
ee a 
