172 MADREPORARIA. 



stock that they rise as bundles of twisted lamella?, the bundles expanding as they rise. The 

 form which results is usually columnar, but may be bluntly conical. Cf. Diagram D, p. 24. 



G. Maldives 2. 



G. Maldives 3. 



G. Red Sea 1. 



G. Red Sea 2. 



G. Red Sea 3. 



G. Red Sea 4-. 



G. Red Sea 6. 

 Doubtful :— 



G. Great Barrier Reef 3. Oval, but due to great rapidity in calicular growth, which 

 is not the case in the oval growth-form proper (see below). 



G. Seychelles 1. 



G. Singapore 3. 



G. Tonga Islands 3. A flat-topped, shallow, inverted cone. 



G. Paris Basin 13. This is even more doubtful than G. Tonga Islands 3. 



E. Branching, 



Branching may be produced along at least two quite different lines (a) by the forking and 

 diverging of thin columns (Diagram E, p. 24), and (b) by the running out, curling up and 

 subsequent proliferation of lobes from the edges of explanate stocks. This latter is rare. 



(a) G. Singapore 1. 



G. Singapore 5. 



G. China Sea 5. But perhaps belongs to (b) below. 



G. Persia 2. 



G. Vicenza 1. 



G. Vicenza 2. \ 



G. Vicenza 7. 



G. Vicenza 12. 



G. Verona 1. 



G. Vienna Basin 3. 



G. Dax 1. 

 Doubtful :— 



G. Sind 5. 



G. Oberburg 1. 



G. Oberburg 2. 



G. Somaliland 1. 



G. Egypt 1. 



G. Vicenza 8. 



G. Vicenza 10. 



G. Vicenza 13. 

 (b).... The only specimen which shows this beyond doubt is 



G. Great Barrier Reef 12. 



G. Great Barrier Reef 1 does not actually branch, but shows how such branching can 

 be started by the curling up of marginal lobes. 



