SOME POINTS IN NATURAL HISTORY OP FUNGIA. 361 
After the disc has become distinctly formed, though the 
breadth it may have attained is very variable, a remarkable 
process sets in, which results in its separation from the stalk 
which has hitherto supported it. In a plane at right angles to 
the axis of the stalk, at a point where the upper part is 
beginning to widen out, absorption of the calcareous skeleton 
takes place, which goes on till the disc is connected with the 
stalk so weakly that a very small force is needed to set it free. 
It often happens that the disc falls off when the object on 
w T hich the Fungia is growing is lifted from the water. 
When the disc is set free it has a round scar in the middle 
of the under surface which corresponds with a similar scar at 
the summit of the stalk. In the scars the following parts of 
the skeleton are exposed, with the soft tissues investing them. 
On the outside there is a section of the thecal wall. Passing 
from this towards the centre are sections of the septa, and 
these unite with the trabeculae which fill in the middle. In 
the disc there is no direct communication with the gastric 
region, except through the interspaces among the trabeculae. 
The surfaces of the calcareous structures where absorption has 
taken place are white and opaque as compared with the general 
appearance of the hard parts of the Coral. 
The disc thus liberated is carried into some depression in 
the reef, where it lies unattached, leading an independent 
existence. The scar on the aboral surface becomes covered in, 
and though it remains distinguishable for some time, ultimately 
all trace of it is lost. On the separation of the disc the stalk 
is left with a truncated top, slightly depressed in the middle. 
The first change which takes place that is visible in dry 
specimens is in the state of the septa (Fig. 2). These, instead 
of terminating in broken edges, throw up delicate fluted laminae 
with serrated edges, which project above the level of the other 
structures of the scar. 
A mouth is formed in the centre, and the lips appear, in 
spirit specimens at least, to be almost in contact with the 
trabeculae below. As the septal laminae rise higher a thecal 
wall becomes formed round them, in some places continuous 
