178 MADREPOBABIA. 



G. Vicenza If.. 



G. Vicenza 5. Septa so wavy as to obscure the radial symmetry. 



G. Vicenza 8. 



G. Vicenza 9. 



G. Turin 1. 



(d) When the colony is very thin, the whole skeleton is reduced in size, and the walls are 



nearly flush with the surface. 



a. The surface is composed of a mosaic of granules, which are the tips of the 

 dwarfed vertical trabeculse. 

 G. North- West Australia 2. 

 G. Cliina Sea 2. 

 G. Maldives 1. 

 G. Paris Basin 2. 

 /3. The surface is composed of horizontal flakes, the horizontal skeletal elements 

 being developed at the expense of the vertical trabeculse. 



G. China Sea 3. A Porites showing the same specialisation conies 

 from the same locality. Cf. G. Paris Basin 6. 



(e) If the encrusting colony deepens, then the walls tend to rise in height and to be 



thinner and sharper, and the septal formula may be obscured by the greater depth 

 of the calicles. 



G. Great Barrier Beef 9. 



G. Great Barrier Beef 11. Perhaps to B (6). 



G. North- West Australia 4- 



G. Verona 2. 



G. Paris Basin 1. 

 Doubtful ; — 



G. Egypt 1. 



The thickening of the stocks is associated with the formation of calicles with high walls 

 as described under the next heading. But before leaving the primitive type of calicle and its 

 variations, it should be re-stated that, whenever thin edges of colonies, no matter of what form 

 of growth, start expanding, the calicles produced are always of the primitive type. But in 

 every case these new calicles also show clear traces of the habit of the calicles typical of the 

 particular colony to which they belong. Instances of this may be seen in the illustrations) 

 cf. PL II. figs. 2 and 3, PI. III. figs. 7 and 8, PI. V. figs. 1 and 2, PI. VI. figs. 1 and 2, 

 PI. VIII. figs. 1 and 2, etc. 



B. Calicles with High Walls. 



The increased height of the wall leads to the deepening of the fossa, and the sinking away 

 of the intracalicular skeleton, which is variously modified and obscured. 



(a) Walls thick. 



a. Showing radial symmetry in their component elements. 

 G. Tonga Islands 1 



G. Tonga Islands 2 I , ,. • ***','-««% 



G. Tonga Islands 8 | bufc tendm g towarda D <* 180 > 



