360 
J. J. LISTER. 
base, and have vertical thecal walls. The youngest that I 
found have six septa conspicuously larger than the rest (Fig. 
1), one at either end of the long axis, passing through the 
mouth, and two symmetrically placed on either side. In the 
intervals smaller septa have made their appearance, but they 
Fig. 1. — A young fixed stock of Fungia(sp.F) X about 25. From a speci- 
men preserved in spirit. 
are lower and do not approach so near the centre as the six 
large ones. In each interval there is one in the centre and 
two small ones on either side of it. The appearance of fresh 
septa does not, however, take place quite regularly, for while 
in one interval between the primary septa there may be three 
smaller ones well developed, in another the central one alone 
may be only just discernible, at least in spirit specimens, in 
which the skeleton is invested with the soft tissues. 
The young stock has, as has been stated, vertical thecal 
walls. After a certain, apparently very variable, height is 
attained the upper part begins to widen out, forming at first a 
very shallow cup with thecal walls facing outwards and down- 
wards, and finally a disc, depressed in the centre, with the 
thecal walls facing directly downwards. The cup or disc is 
attached by the narrow stalk, the first formed part of the 
stock. 
