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J. J. LISTER. 
with the thecal wall of the stalk, but generally springing a 
little within its margin, so that the edge of the old thecal wall 
remains as a prominent ridge round the stalk. A new cup is 
thus formed, not as a bud but as a product of the growth of 
the structures already existing in the base of its predecessor. 
As its walls grow higher they become more and more expanded 
Fig. 2. — A nurse stock of Fungia (sp. ?), from which a disc has been recently 
separated X 3. The formation of a new disc has begun, as is indicated 
by the laminae which have been formed on the edges of the septa in the 
stalk of the old one. The ridge half way down the Coral indicates the 
line of separation of an older disc. From a dried specimen. 
outwards, until a new disc is formed supported on a short 
stalk which springs from the point where the first disc was 
separated. 
This second disc in its turn is set free by absorption of the 
calcareous skeleton at a point where the stalk begins to 
widen into the disc, and in due course a third disc is formed. 
As the process is repeated the stalk grows in height step by 
step, each new disc that is formed being detached at a point 
above that from which its stalk springs. These successive ad- 
ditions are indicated on the common stalk by ridges which 
mark the planes where discs have been separated. 
The specimens obtained show many instances of the forma- 
