62 G. E. ANDERSON 
finally it reaches a point where it will be nearly at right angles to the 
inner part or attached border, which is at this time about parallel in 
position to the outer wall. This inner portion of each septum in this 
manner forms a part of the inner wall as fast as the septa become 
radially directed (Figs. 2, 3). 
In a later section (Fig. 2) the alar pseudo-fossulae have been 
spanned by a dissepimental bridge which is here slightly thinner than 
the normal width of the inner wall. The inner wall ends in two 
septa, one on each side of the cardinal septum as would be expected, 
unless the latter should take part in the formation of the inner wall 
which, however, has not been observed. 
In a section of a later stage 
(Fig. 3) the inner wallisof uniform 
thickness and ends in the septa 
nearest the cardinal fossula, as 
in Fig. 2. The neck between the 
cardinal fossula and the inner 
central area has become more 
narrow. ‘The cardinal septum 
has been reduced in size to that 
of a tertiary septum. 
This mode of development of 
the inner wall extends from the 
: alar septa as initial points 
taken 5™™ higher up than section of 5 z 
Fig. 2. a. Thealarsepta. Diameter towards the cardinal eo and 
of corallite, 4m™, simultaneously from either side 
of the counter septum as another 
initial point toward the two alar regions. There would, therefore, be 
a break in the inner wall in the region of the cardinal septum, and two 
breaks, one at each of the alar regions where growth from the counter 
quadrants ceased. The two latter are early spanned by the deposi- 
tion of material of a similar nature to that of the septa, thus uniting 
the groups and making the septal structure more firm. In Fig. 2 this 
growth is in the course of construction and is completed before the 
stage in Fig. 3 is reached, as here the wall is of uniform thickness 
throughout—and the “bridges” spanning the pseudo-fossulae in Fig. 2 
are thoroughly incorporated. This eliminates the last trace of the 
Fic. 3.—Section of same corallite 
