80 



ANTHOZOA. ZOANTHAR1A 



and a fold hangs over the outside (fig. 22, 6, 7); but as 

 the septa, theca, etc., increase in height the lower part of 

 the visceral chamber (in most cases) becomes more or less 

 completely cut off by the development of dissepiments or 

 tabulae, below which the soft parts do not extend. As 

 growth proceeds more of these partitions are formed, and 

 eventually a large part of the coral ceases to have any 

 direct connexion with the polyp. 



Some corals remain simple (i.e. consist of a single 

 individual throughout life). Others, which are simple in 

 the young state, afterwards become compound and form 



Fig. 26. A. Dendrophyllia nigrescens, showing corallites which have 

 heen produced by lateral budding. Recent, x \. B. Cyathophyllum 

 truncatum, showing calicular budding, Wenlock Limestone. Natural 

 size. C. Cladochonus crassus (seen from above), showing basal 

 budding, Carboniferous Limestone. Natural size. 



colonies, either by giving off buds, or by fission. In 

 budding, new individuals may arise from the part of the 

 polyp which extends outside the theca (fig. 22, 6, 7), in 

 which case a branching coral like Dendrophyllia (fig. 26 A) 

 is frequently formed ; this mode of increase is termed 

 lateral budding. In other cases buds arise on the upper 

 surface of the old polyp, and then the young corallites are 



