( 87 ) 
On the Minute Structure of a Species of Faujasina. Bj Pro- 
fessor W. C. Williamson. Communicated by Matthew 
Marshall, Esq. (Read June 22, 1851.) 
In the last memoir on the Foraminifera which I laid before the 
London Microscopical Society, I pointed out the existence of 
a curious system of tubes and canals, penetrating the parietes 
and septa of several species of Foraminiferous shells. In 
Polystomella crispa these chiefly presented themselves in the 
form of large canals passing through the calcareous umbilical 
regions. In some species of Nonionina and Amphistegina 
they existed as a dense network of minute canals, having their 
external orifices at the peripheral margins of the discoid shells. 
In the latter examples the canals were of small diameter, and 
their use in the economy of the living animal very dubious. 
On making a number of sections of a species of Faujasina 
(D'Orb.) from Manilla I discovered the existence of a much 
larger and more interesting arrangement of tubes than any 
that I had previously seen. This shell is constructed on the 
inequilateral plan of the common Truncatulina tuherculata. 
Its inferior surface is flat, the corresponding extremities of 
the segments being arranged on a nearly uniform plane. As 
successive convolutions have been added to the antecedent 
ones, they have assumed the arrangement of a series of hollow 
cones placed over one another, the additions to the length of 
each new segment being confined to its upper extremity. 
Hence, whilst inferiorly all the convolutions are visible, on the 
upper surface we only see the outermost one presenting the 
aspect of a truncated cone. 
Fig. 1, PI. X., is an enlarged representation of the lateral 
appearance of the shell, viewed as an opaque object. Whilst 
the vertical septal lines (1 d) are translucent, the intervening 
parietes of the segments (1 g\ in which the minute foramina 
exist, is of an opaque gray colour. The inferior peripheral 
margin (ly*), and its continuation at the flat inferior surface, 
constituting the spiral septum (fig. 2 e) separating the con- 
volutions, exhibit the same translucent aspect ; as does also 
the truncated apex of the cone (1 c?'), towards which all the 
vertical septa converge. In nearly all the Foraminifera a 
translucent line appears to mark the existence of a subjacent 
septum. The segments, which do not extend to the summit 
of the shell, communicate with one another by one very large 
oral aperture (1 e). 
Along each of the vertical septal lines (1 c?) there exists an 
irregular double row of very distinct pits or depressions (fig. 
6 f). Similar pits are seen inferiorly in the radiating septa 
VOL. I. h 
