538 
DE. CAEPENTEE’S EESEAECHES OX THE FOEA^nXITEEA. 
figure, not merely of the shell, but also of the pseudopodia protruded from various parts 
of its surface ; as well as to make preparations of the sarcode-body of the animal, by 
dissolving away the shell in dilute acid. He does not seem, however, to have had the 
advantage of a full knowledge of Professor Williamson’s memoir; his acquaintance 
with it being apparently limited to the abstract of it contained in ‘ L’Institut’ (Xo. 787) ; 
and I find in his description of the shell a confirmation of the belief I have already had 
occasion to express, that he has not availed himself as fully as is desirable of the mode 
of examining the intimate structure of these minute objects by the preparation of very 
thin sections. In every point, in fact, in which he difiers from Professor Williajison, 
I am satisfied that the truth Lies with the latter ; and this not merely on account of the 
enthe coincidence between the results of my own inquiries into the structui'e of Poly- 
stomella crispa and those of my accomplished predecessor, but also because our views 
are in every respect borne out by the structure of the much larger and more highly 
developed form of Polystomella which I am presently to describe. One point in Pro- 
fessor Schultze’s description, however, requhes special notice. He states that each of 
the crenulated prominences which are seen on the surface of the lateral walls of the 
chambers is traversed longitudinally by a wedge-shaped fissure, that is narrowest as it 
approaches the septal band, near which it penetrates the carity of the chamber, whilst 
it becomes shallower as it widens out at the part where the crenulation merges in the 
smooth wall of the shell. I expect to be able to show that the supposed “ fissures ” of 
Professor Schultze no more communicate with the carity of the chambers, than do the 
“ fossettes ” of M. d’Okbigny ; but that they are really the outlets of the canal-system, 
whose existence in Polystomella has not been discovered either by Prof. Schultze or by 
Prof. Williamson, but which attains an extraordinary development in the type which 
has specially fallen under my observation. 
178. The specimens of Polystomella, of which I have now to give an account, were 
chiefly collected by Mr. Jukes in his Australian di'edgings; I have met with the same 
form, however, in Mr. Cuming’s Philippine collection ; and I have reason to beheve it 
to be generally difiused through the Indian and Polynesian seas. It seems to be the 
P. craticulata of Fichtel and Moll. The empty shells are occasionally the subjects of 
that very curious infiltration of silicate of iron, to wliich attention was first dhected by 
Professor Eheenbekg as a peculiar mode of fossilization of Foraminifera, — causing in- 
ternal “ casts ” of their chambers to be preserved long after their shells have been 
destroyed, — in his memoir ‘ tlber den Gruensand und seine Erliiiiterung des organischen 
Lebens”^, and which was soon afterwards showm by Professor Bailey f to be taking 
place at the present time over certain parts of the ocean-bottom. I have recently been 
enabled, through the kindness of Mr. W. K. Paeker, to examine a number of most 
perfect and beautiful “casts” which he has obtained, not merely of fragments, but of 
the entire animal of this type of Polystomella, by treating w ith dilute acid shells wiiich 
* Abbandlungen der Konigl. Akad. der 'Wisseuscbaften, Berlin, 1855. 
t Quarterly Journal of Microscopical Science, vol. v. p. S3. 
