REPOET ON THE FORAMINIEERA. 
xiii 
of Sphceroidina retained the form of the pseudopodial tribulation of the shell as 
minute cylindrical projections from the surface. So far as the general fact of the 
presence of the animal sarcode in bottom-specimens of pelagic forms is concerned, these 
observations possess no novelty, but are simply confirmatory of the results set forth by 
many previous writers ; indeed, the sarcode-contents of the shells of bottom -Globigerince 
were fully and accurately described by Wallich more than twenty years ago. 
The distribution of the little northern species, Globigerince pachyderma, presents some 
features of interest bearing upon the matter in hand. This is a strongly marked form, 
and easily recognised. It is common in the Arctic Seas, generally occurring in company 
with small specimens of the typical Globigerina bulloicles. In the Faroe Channel, as is 
well known, there exist, side by side, two sharply defined areas, of which the bottom 
temperature differs to the extent of 16° or 17° Falir., though there is no material 
difference as to depth, and the temperature of the surface-water is practically uniform 
over the whole. On the cruise of the “Knight Errant” bottom-specimens of Globi- 
gerina pachyderma were dredged abundantly in the “ cold area,” and, more sparingly, at 
one Station in the “ warm area.” In the tow-net gatherings Globigerina bulloides was 
equally plentiful over the “ cold ” and “ warm ” areas ; but neither there, nor hitherto in 
any other region, has Globigerina pachyderma been met with at the surface. It is also 
worth mentioning that occasional specimens of the latter species have been found in the 
Red Clay of the abyssal depths of the North Pacific and elsewhere. 
In alluding to the comparative thickness of the shells of surface- and bottom-speci- 
mens, some reservation was made with respect to the Orbulince. As commonly taken 
in the tow-net, the calcareous investment of Orbulina is a globe of extreme tenuity and 
transparency, the exterior of which is usually provided with delicate spines, sometimes of 
great length, but more often relatively short. This outer test encloses a small, internal, 
polythalamous, Globigerina-like shell, which as a rule is also more or less spinous. 
Compared with these, bottom-specimens are stoutly built, and very variable amongst 
themselves in shell-texture and other particulars. Perhaps the most noteworthy 
structural feature of the latter is the way in which the shell is formed of a number of 
distinct layers, sometimes four or five separate shelly envelopes, one enclosed within the 
other, yet without any apparent adhesion of their walls. The majority of bottom-speci- 
mens, especially those of large size, contain no internal “ Globigerine ” shell. 1 
To revert to the pelagic specimens. In a gathering taken with the tow-net sunk to 200 
fathoms an Orbulina was met with, the shell of which measured nearly -g-^Qth inch ('046 
mm.) in thickness ; this was so exceptional that it attracted instant attention. I have 
1 Since these introductory paragraphs have been in type, I have received from my friend M. Schlumberger a copy 
of a note “Sur l’Orbulina universa, d’Orb.” (dated 21st April 1884), in which the occurrence of specimens with and 
without the internal. Globigerina-\ike shell is brought forward as an example of “ dimorphism” (see p. viii.), the single- 
chambered shell being the honiologue of the large initial segment of other Foraminifera. Is it possible that of the 
“ pair,” in this instance, one form normally inhabits the surface-water the other the bottom-ooze ? 
