4 Mr. H. M. Bernard on (he 



The following pages sum up the principal conclusions lie has 

 arrived at. 



The most important stage to establish in an evolutionary 

 history is the first, or that which we may consider as the 

 first, inasmuch as from it all the modifications we wish to 

 compare can be deduced. The first stage in the evolution of 

 the coral skeleton was first dimly recognized by me in the 

 minute sawcer-shaped cups of young Madreporidan colonies — 

 so young as to consist only of a parent calicle and one or two 

 daughters. In none of the Madreporids have I yet found the 

 earliest stage in which the cup containing the parent alone 

 was cw/>-shaped. Such a stage, however, may be legitimately 

 assumed. 



The discovery of such colonies made three points clear to 

 me : — 



1. The parent calicle of a colony rises out of a basal cup — 

 the Peototheca*. 



2. This prototheca is not a composite structure, but a 

 morphological unit, the rim of which can be bent up, flattened 

 completely down, and indefinitely expanded in any direction 

 as a film, from the upper surface of which, as originally 

 from within the cup, the coral skeleton arises. 



3. This film is the Epitheca f. 



These conclusions received complete confirmation from a 

 study of the Palaeozoic form Favosites and of its modern 

 descendant Alveopora. I have already described and figured 

 the prototheca of the latter genus J. Its rim, as shown in the 

 figures referred to, does not usually flatten down, but grows 

 upwards and outwards to form the irregular film-like invest- 

 ments characteristic of the colonies of this genus. 



In both cases — that is, in Madreporidse and Favositidaj 

 alike — it was easy to see the bars of the intracalicular skeleton 

 rising directly out of the wall of the cup as internal projections 

 from its surface ; this point is of importance, because 

 von Koch, whose developmental researches also revealed to 

 him the prototheca, was led by what he saw to regard it as a 

 composite structure consisting of a basal portion (" Basal- 



* Lindstrom suggested the word " initium " for the earliest cup-like 

 skeleton ; the term u prototheca " was suggested to me in conversation 

 by my friend Prof. Jeffrey Bell. 



t The fact that the skeletal elements rise from the surface of the 

 epitheca was pointed out by Martin Duncan in 1884 (Journ. Linn. Soc, 

 Zool. xvii. p. 361) as indicating the importance of that element of the 

 coral skeleton. 



X Journ. Linn. Soc, Zool. xxvi. 1898, p. 495, pi. xxxiii. 



