16 Miss M. M. Ogilvie. Microscopic and Systematic [Nov. 21, 



Laving certain features, in common with the Madreporidae, differ 

 essentially in septal structure, and are regarded as a group of 

 Madreporaria which branched off at a very early age from the main 

 ancestral stem of Zaphrentidae, and followed an independent line 

 of development. 



The author's results bear inevitably to the conclusion that the 

 suborder Madreporaria Rugosa erected by Edwards and Haime 

 draws an entirely artificial barrier between Palaeozoic Madreporaria 

 and the younger suborders M. Aporosa and Perforata Ed. and H. In 

 the second part of the present paper the author annuls all three sub- 

 orders and follows out the evolution of Madreporaria in the light of 

 the general morphological results arrived at in the first part of the 

 paper. Haeckel's terms of " Tetracoralla " for the M. Rugosa and 

 Hexacoralla for the M. Aporosa and Perforata only gave a stronger 

 expression to Edwards and Haime's convention of tetrameral and 

 hexameral symmetry of the septa. And although several authors 

 have from time to time pointed out the inappropriateness of erecting 

 subdivisions on the feature of septal symmetry, nothing farther has 

 been done. Even now, in current literature, one may find the term 

 Rugosa = Tetracoralla set in contradistinction to Madreporaria = 

 Hexacoralla ! 



From the standpoint attained by her own investigations, the 

 author then traces the series of changes which appeared within the 

 group of Madreporaria during the course of the geologic ages. Some 

 of the more important and general of these evolutionary changes may 

 be shortly enumerated : — 



(1) Tabula? became modified centrally as columella and pseudo- 

 columella, more seldom became vesicular. 



(2) Instead of one to four basal pits (fossulae) for the reception of 

 specialised reproductive mesenterial filaments, the whole base of the 

 calyx became deepened, usually around the axial columella or pseudo- 

 columella. 



(3) Septa became more prominent and exsert in growth ; their 

 structure became more elaborate, their surfaces fluted and richly 

 granulated, their edges knobbed, toothed, serrated, spined. 



(4) The " rugose epitheca " became tardy in growth, and was 

 replaced functionally by a theca or pseudotheca. 



(5) Vegetative increase was facilitated by the specialization of an 

 "edge-zone" around the polyp (represented by the " costate " por- 

 tion of a calyx, or its ancient homologue, the peripheral " dissepi- 

 mental zone" of Cyathophyllids). 



(6) The "pinnate insertion " of septa demonstrated by Kunth in 

 primitive corals became gradually a feature of embryonic calyces, and 

 then vanished. But the embryonic mesenteries appear in recent 

 types in the same "tetrameral " order as the S3pta did in the mature 



