﻿50 MPv. T. F. SIBLY 0:S THE FAFNAL SUCCESSION IN THE [Feb. 1 908, 



development of D^, possessing a typical brachiopod-fauna, but an im- 

 poverished coral-fauna. Moreover, the influence of these conditions 

 seems evident in the fact, that even where the Lonsdalia-subzone 

 of the western part of the area presents its most nearly typical 

 development, the coral-fauna is considerably less rich than in that 

 really-typical facies which is coextensive with the eastern half of 

 the area. That is to say, the difference between an eastern 

 and a south-western facies of D,, which has already 

 been pointed out, may probably be attributed to the 

 influence of those conditions which determined the 

 presence of the ' brachiopod-beds' in the western part 

 of the area. 



To sum up, it may be stated that the Lonsdalia-subzone of the 

 Midland area exhibits two very distinct facies, which are as 

 follows : — V 



(i) A coral-and-brachiopod facies, in which the coral-fauna and 

 the brachiopod-fauna are equally predominant. This, which i& 

 most typically developed in the eastern part of the area, is by far 

 the more extensive facies, and is to be regarded as typical. 



(ii) A clearly- developed, yet localized brachiopod-facies, found 

 only in the western part of the area. Here the coral-fauna is 

 very feebly developed, but the brachiopod-fauna, while retaining^ 

 all the essential features of the typical development, is considerably 

 enriched. 



It is possible that the ' brachiopod-beds ', while mainly repre- 

 senting D.,, encroach on the succeeding subzone. That is to say,, 

 the typical Cyathaai^onia-s-abzone is perhaps locally replaced, in part 

 at least, by a portion of the ' brachiopod-beds '. In the absence of 

 stratigraphical evidence, I am unable to form a definite opinion on 

 this question. 



D3 = Subzone of Cyathaxonia rushiana. 

 Faunal list : — 

 Corals : 



Cladochcmus hacillarms (M'Coy). 



Cladochonus crassus (M'Coy). 



Zaphrentids of numerous types, in- 

 cluding ZaphrentAs Enniskilleni, 

 Ed, & H. ; Densiphyllids ; and forms 

 of Amplexi-Zaphrcntis, Vaughan, 



Cyathaxonia costata, M'Coy. 



Cyathaxonia ruahiana, Vauglian. 



Syringopora cf. distans, Fischer. 



Favosites parasitica (Phil.). 



Beaumontia aff. Egertoni, Ed. & H. 



Michelinia gloinerata, M'Coy. 

 Campophyllum aff. derbiense, Vaughan 



(MS.). 

 Cyathophyllum regium, Phil. 

 Lithostrotion junceum (Flem.). 

 Koninckophylloid Lithostroticm. 

 Koninckophylhim spp. 

 Bihunophyllum sp. 



Clisiophyllum aff. curkeenense (1)^ 

 Vaughan. 



Cyclophyllum sp. 



