288 Royal Society :—On the Nature of the 
pseudopodial orifices, contrasted strongly with the larger and 
thicker shells of the specimens brought up by the sounding- 
apparatus from the bottom immediately beneath, in which the 
shells were thick and those orifices obscure. It is obvious that 
if this extraordinary abundance of Globigerine life in the bottom- 
water was the result of subsidence from the surface or sub-surface 
stratum, and was merely preparatory to the deposition of the shells 
on the sea-bed, there should have been a correspondence in size 
and condition between the floating shells and those lying on the 
bottom immediately beneath them; whereas no contrast could be 
more complete, the impression given by the superficial aspects 
they respectively presented having been fully confirmed by sub- 
sequent careful investigation. 
Prof. Wyville Thomson and Mr. Murray, who notice this con- 
trast, attribute it to the death of the shells which have subsided to 
the bottom—being apparently unaware that the observations of 
Dr. Wallich, with which my own are in entire accordance, leave 
no reasonable ground for doubt that it is a consequence of their 
continued life. For it is clearly shown, by making thin trans- 
parent sections of the thick-shelled Globigerinw (an operation 
which needs a dexterity only to be acquired by long practice, and 
which is much facilitated by an ingenious device invented by Dr. 
Wallich *), that the change of external aspect is due to the 
remarkable eaogenous deposit (a rudiment of the ‘intermediate 
skeleton” of higher Foraminifera) which is formed, after the full 
erowth of the Globigerina has been attained, upon the outside of 
the proper chamber-wall—so completely masking its pseudopodial 
orifices, that Prof. Huxley at one time denied their existence. This 
deposit is not only many times thicker than the original chamber- 
wall, but it often contains flask-shaped cavities opening from the 
exterior, and containing sarcode prolonged into it from the sarcodic 
investment of the shell. Illustrations of this curious structure are 
given by Dr. Wallich in figs. 17 and 18 of plate vi. of his ‘ North- 
Atlantic Sea-bed;’ and I here subjoin a representation of it, 
Section of Shell of Globigerina, 
showing the distinction between the 
original proper wall of the chambers 
and the secondary exogenous de- 
posit, with the flask-shaped cavities 
in the latter opening externally and 
containing sarcode like that which 
fills the chambers. 
kindly given me by Dr. Wallich twelve years ago, which further 
* Ann. & Mag. of Natural History, 1861, viii. p. 58. 
