1 76 MADREPORAKIA. 



Table IV.— ANALYSIS AND DISTRIBUTION OF THE MORE EASILY 

 DEFINABLE TYPES OF CALICLE. 



One result of the survey of all the kuown specimens of Goniopora contained in the foregoing 

 pages is to enable us to differentiate certain fairly well marked types of calicle. At the outset 

 tliis seemed hopeless on account of the multitude of minute structural variations in wall, 

 septa, coluuiella and pali. Quantitative distinctions were out of the question,* while 

 qualitative distinctions seemed to baffle definition. Further practical difficulties may be 

 mentioned in the facts (1) that the calicles of many fossil ibrms are known only from sections 

 which give no information as to the shape of the wall, tlic most important of all the 

 characters, and (2) that the calicles vary greatly on one and the same colony. In the latter 

 case we have succeeded in finding out at least one of the laws of this variation. I refer to 

 that according to which the calicles tend to revert to the primitive low-walled type on any 

 edge of a colony which starts growing as a thin creeping layer. 



The following are the most important morphological results of our inquiry with regard to 

 the calicles. (a) We can define tlie primitive type of calicle. (h) The possible relations of its 

 septal formula to the septal formula of the kindred genus Pontes has been discovered, 

 (c) Several types of calicle, all deducible from the primitive type, stand out clearly, and {d) a 

 start has been made in correlating these types with definite methods of growth. For structural 

 details, see the Introduction, pp. 18 et seq. 



A. TJie Primitive Type of Calicle. 



With low, thick wall, in the structure of which radial symmetry is still traceable, with 

 the typical septal formula and pali, and with shallow fossa. The lateral budding of such 

 calicles would necessarily result in explanate growths. 



(a) With radial symmetry in the texture of the wall. 



G. Great Barrier Reef 1. On the explanate portions. 

 G. North- West Australia 3. 

 G. Mauritius 1. On the explanate portions. 

 Doubtful :— 



G. Sind 3. " WaUs frequently reticular." 

 G. Paris Basin 1. Or under E. 

 Goniopiora xg. 



(h) With the wall texture melted down into a reticulum. The more plastic ccenenchyma 

 thus produced is favourable for interstitial budding, and columns may result, — a 



* I have, however, added lists of the very small and the very large cahcled forms, although 

 doubtful as to its utility. 



