REPORT ON THE FORAMINIFERA. 
XI 
rest are very common. Other Pulvinulince , occurring abundantly in dredgings from 
great depths, have never been found in the tow-net gatherings. 
By reference to Distribution Table II. the extent and character of the Bhizopod-fauna 
of Globigerina Ooze will be seen at a glance. The number of species contained in the 
different samples of bottom-mud included in the Table ranges from twenty to ninety-five. 
Taking three typical examples, each yielding about fifty species of Foraminifera, the 
average proportion of pelagic to bottom-species is somewhat less than one to four ; but in 
the proportionate number of specimens the pelagic forms are enormously in excess. 
Inasmuch therefore as the sea-bottom over a very large portion of the world consists of a 
deposit of which these pelagic Foraminifera form collectively the chief constituent, 
everything connected with their manner of life possesses a certain amount of importance. 
Wide differences of opinion have existed with respect to the actual relation subsisting 
between the Foraminiferal fauna of the surface, as represented by the species above 
enumerated, and that of the sea-bottom ; 1 the points admitting of debate, however, have 
been gradually narrowed, and at the present time appear to lie within very small 
compass. The chief question concerning which naturalists are not agreed is whether 
the species referred to are exclusively pelagic, and pass the whole of their existence as 
free swimming organisms, or whether they have also the power of living, and do 
live, more or less, at the sea-bottom. 
In one of the preliminary papers on Challenger Foraminifera 2 I stated briefly the 
results of my earlier investigations in connection with this subject, together with the 
inferences they suggested. During the last three or four years, however, I have had the 
opportunity of examining much more fully the large collection of surface-gatherings 
obtained during the Challenger Expedition, as well as important material collected by 
Mr. Murray on the cruise of the “Knight Errant” ; and as there are certain points in 
which my previous experience has not been entirely confirmed, I may be permitted to 
make a few remarks, both by way of correction and in order to explain more fully, in some 
respects, what appears to me to be the present aspect of the question. The observations 
requiring correction are those relating to the comparative dimensions of the surface- and 
bottom-specimens of the same species, and the thickness of the shell- wall. In the various 
batches of surface-organisms which had come under my notice at the time I wrote, not 
1 See — Wallich, 1862, The North Atlantic Sea-bed ( Van Voorst ) ; 
Major Owen, 1866, Journ. Linn. Soc. Lond., vol. ix. (Zool.) p. 147 ; 
Wyville Thomson, 1874, Proc. Roy. Soc., vol. xxiii. p. 32 ; 
Carpenter, 1875, Ibid., p. 234 ; 
Wallich, 1876, Deep-sea Researches on the Biology of Globigerina ( Van Voorst), 
a 3 well as numerous other papers and notes, earlier and later, by Ehrenberg, Miiller, Bailey, Haeckel, Wallich, Carpenter 
and Thomson, Jeffreys, Murray, Schacko, &c. 
1 have endeavoured as far as possible to limit the scope of the present remarks to matters within my own observa- 
tion, and have made no attempt to summarise the labours of previous writers, still less to pass judgment upon them. 
2 'Quart. Journ. Micr. Soc., 1879, vol. xix., N. S., p. 292. 
