Prototlieca of the Madreporana. 31 



The term " athecalia " of Ortmann, it may be remarked, lias 

 not been very well received, for it is certainly not true that 

 the corallites, say, of Madrepora have no thecaj. The very 

 opposite is the case; the thecas are most pronounced. What 

 we want to express is that these theca; are morphologically 

 distinct from the original theciie of the Madreporaria, and no 

 better term could be employed than that here suggested — 

 pseudotheca. 



I am aware that a long critique of the views and suggestions 

 of other workers on the subject of the wall should be offered 

 before proposing a revision. But I have the excuse that the 

 revision of the terminology here suggested rests upon a 

 somewhat far-reaching revision of the skeleton. A closer 

 comparison of the terminologies would involve a closer com- 

 parison and criticism of the views on the wall-structure of each 

 different author, some of wdiich are, I confess, not always 

 clear to me. Indeed, we seem to have had enough of detailed 

 and complicated discussion. The great want is some simple 

 working hypothesis which will enable us to coordinate the 

 facts. 



My own work has convinced me that some order appears 

 out of the chaos if we recognize the prototheca and give it 

 the important place in the morphology of the coral skeleton 

 here all too briefly sketched. 



In conclusion, I should like to emphasize the fact ihat this 

 paper is intentionally devoted to the prototheca and its con- 

 centric modifications — that is, to those modifications which 

 alter its cup-shape concentrically. Only occasionally and 

 where necessary reference has been made to the great and 

 complicated system of radial wall-folds which are the most 

 characteristic structures of the stony corals. These have, 

 however, claimed the attention of workers too exclusively in 

 the past. We shall only be able to obtain a true insight into 

 the evolution of the coral skeleton when we understand both 

 systems of modification — the more primitive concentric and 

 the later radial — and can trace out their influences on one 

 another. It is to me a matter of sincere regret that this 

 paper was not published prior to Miss Ogilvie's comprehensive 

 and patient treatise on the septa, for her valuable observations 

 would then, I am convinced, have admitted of more precise 

 and coherent treatment. 



EXPLANATION OF PLATE I. 



Fi(j. L The three earliest growtla-periocla of <i primitive Madreporarian. 

 The thiclc hasnl part is the prntotheoa (^en:i. !>tn'rf.), see tio-. 2. 



