Prototheca of the Madreporaria. 17 



prototliecae were brouglit about deserve mucli more attention 

 than has ever yet been bestowed upon them. While I would 

 not deny that the rise of the radial ingrowths from the inner 

 (or upper) face of tlie prototheca, that is the septa, on which 

 Milne Edwards's classification is mainly based, may not supply 

 during this period the best taxonomic characters, I still do 

 not think that the variations in the curve of the prototheca! 

 rims, or, in other words, the shapes and dispositions of the 

 tabulce, can be so completely ignored as has hitherto been 

 done. A few examples will show what I mean. 



Diagrams figs. 13 a-/ show some of the forms assumed by 

 the prototheca of adult single Palaeozoic corals. They were 

 built up of series of such prototheca^ fitting into one another 

 and usually raised above one another, sometimes by septal 

 folds or ridges, sometimes by vesicular arrangements of the 

 tabulae of whicli only the edges showed clear and sharp, or 

 sometimes the sloping sides being vesicular, while the more 

 or less flattened bases are smooth. 



It is impossible now to say how far these foldings outwards 

 and downwards of the rims are of the nature of accidental 

 variations. But until we know I can hardly think it right 

 to ignore them so completely as has been done, say, in the 

 genus Cyathophyllum as given by Milne-Edwards and Haime. 

 For instance, we find specimens called Cyathophyllum which 

 show the prototheca of the shape given in fig. 13 a (e. g. 

 C. /MrJi'««^wm,Goldfuss*, said by Milne-Edwards and Ilaimef 

 to be C. ceratites, although they themselves give a figure 

 of it which appears to have the prototheca of the form 13 A). 

 Again, Goldfuss [l. c. fig. 8 d) gives other figures of his 

 C. turlinatum with prototheca 13 c, while his C. ceratites 

 (pi. xvii. fig. 2 h) is shown witli prototheca 13 d, with tabulate 

 floor and vesicular sides. This latter M.-Edwards and Haime 

 called C. Decheni with the same form of prototheca as their 

 C. BouchardiX' C. heterophyllum § aj)pears to have a proto- 

 theca of the form, 13^. Goldfuss again gives a Cyatho- 

 phyllum helianthoides (in his pi. xx. fig. 2 e) with the same 

 prototheca, 13 e, as that given for the genus Ptychophyllum. 



It is quite true that considerable variation in the slopes of 

 these flattening rims may be expected. For instance, in 

 Goldfuss's figures of C. helianthoides, just referred to, some 

 have the prototheca 13 c, others wih rims even more convex 



* Potref. Germ. pL xvl. fig. 8 a. 



t Brit. Foss. Corals, pi. 50. fig. 2. 



X Pol. foss. Terr. pal6ozoin[ues, pi. x. fig. 2, 



§ Ibid, pi, X. fig. 1. 



Ann. dl- il%. N, Hist. Ser. 7. Vol. xiii. 2 



