DISTRIBUTION OF OEOWTH-FOBMS. 171 



Doubtful :— 

 G. Australia a. 

 <!. Vicenza 3. 



G. Singapore 6, appears to be passing into the columnar. 

 G. Genoa 1. 

 G. Genoa #. 



C. Columniform. 



We may perhaps distinguish five types of Columniform Gonioporm. 



The first («) might be called pseudo-columnar, for the columns are not due to the direct 

 continuous growth of a colony, but to the gradual piling up of colonies, the successive edges of 

 which remain traceable. Diagram A, p. 24. 



G. China Sea 4 may have been built up in this way. 



b contains those forms which rise into stout round-topped columns without the formation 

 of free edges, and without any great increase in thickness. 

 G. New Ireland 1. 

 G. Fiji Islands 1. 

 G. Great Barrier Reef 11. 

 G. Singapore 2. 

 G. Ceylon 1. 



Doubtful :— 



G. Singapore 6. This seems like a. transition between the hemispherical and the 



columnar. 

 G. New Guinea 2. 

 c contains those columnar forms which are due to the sudden shooting up of the central 

 portion of a colony by the rapid growth of the calicles in height. Diagram E. p. 24. 



(!. Solomon Fslands 1. This coral forks ; but the stem below the fork must have 

 shot up as a thin erect column. 



d. This differs from c in that the column i3 not the growth of a single colony, but groups 

 of columns rise irregularly and adventitiously from the surface of an otherwise purely expla- 

 nate stock by the sudden proliferation of groups of calicles. In the genus Montipora, in which 

 the ccenenchyiaa reaches a climax in its development, such sudden upbursts are very common 

 (see Vol. III. of this Catalogue), but so far only one instance is known in Goniopora. 

 G. Mauritius 1. 



e is the expanding sheaf formation wliich usually results in columns, but is peculiar and 

 important enough to be described under a heading of its own. 



D. Expanding Sheaf Formation. 



This modification of the primitive plano-convex is the most peculiar of all the growth- 

 forms of Goniopora. It is hardly a modification of the true oval, because it is apparently due 

 to great rapidity of calicular growth, although it may lead to the formation of ova] stocks. It 

 appears to be due to such rapid growth of the walls and septa in the central calicles of the 



z 2 



