﻿444 DE. A. YAFGHAN OlSi THE PAUNAL SUCCESSION [Aug. I908, 



(4b) Fauna of D3& (E 22 and R 23). 



In ascending order : — 



(x) includes E 23 5. 



ril22candE23c. 

 (y) includes <^ R 22 ?) and E 23 d. 



[n22a. 



(i) Corals : 



(x) Cladochmms. 



(j) ^yringopora cf. ramulosa (Goldf.), Ed. & H. 



^(x, y) '^MicJielinia tenuisepta (Phill.) (typical form), 



(x) Densiphylloid Zaphrenth (including Z. Omaliusi, var. densa, 



Oarruthers). 

 (x, y) ^Zaphrentis Omalmsi, Tar. ambigua, mut. o- nov. 



(x) Densivhyllum rushianum. sp. nov. 



(x, y) Fseudamplexus spp. 



>(x, y) * Cyathaxonia rushicma, Vaughan. Common. 



(x) Cyatliopliyllum Murchisoni, Ed. & H. 



>(x, y) Dipbyphylloid Lithostrotion. 



(ii) Brachiopods: 



•(x, y) Froductus cf. concinmis, Sow. 



(y ) Froductus margaritaceus (Phill.) ? 



(x) Syringothyris subconica (Mart.). 



Dsb is distinguished from Dsa by the paucity of brachiopods, by 

 the absence (or rarity) of Clisiophyllids, and by the occurrence of 

 a narrow-tubed Michelinia ^ ; the two series are linked by Cyaihax- 

 onia rusliiana which persists, in a mutation, into P. 



The rapid extinction of the Clisiophyllids marks the top of the 

 Avonian in all areas ; the paucity of brachiopods and the prevalence 

 of Miclielinia are phenomena dependent on bathymetric conditions. 



The closer general resemblance of the Dg^ fauna to that of D, 

 suggests that D3J is, on the whole, higher than D^a ; the two 

 divisions (Bg^, D^b) are, however, so closely linked that overlapping 

 is probable. 



The absence of a typical high-D^ fauna suggests that at least the 

 lower part of Dg is a phasal equivalent of D^ — as is also probably 

 the case in Gower. 



(4 c) Fauna of the DP Phase (L 3/ and L 4). 



(i) Corals : 



Syringopora cf. ramulosa (Goldf.), Ed. & H. 



Densiphyllids including 



Zaphrentis Omaliusi, var. densa, Oarruthers. (^ Lane form.) 

 Densiphylloid Zaphrentis, sp. nov. (z^ form from L 21 (^ and Lane.) 



1 The Michelinia of D3J is intermediate between the wider-tubed form of D2 

 and the Michelinoid Favosites of P. 



