﻿Vol. 64.] CARBONIFEROUS LIMESTONE OF THE MIDLAND AREA. 65 



D2 = Subzone of Lonsdalia floriformis. 



Comparing the faunal assemblage of this subzone with that of the 

 Upper BibunopJit/Uum-Zone (DJ of the South-Western Province, 

 the following important points of agreement are evident : — 



(1) The occurrence of Lonsdalia floriformis, Cyathcpliyllum regium, 



Lithostroiion PortlocJci, and Bibunophylla of a more specialized type 

 than tliose found in D^. 



(2) Although the brachiopod-fauna of T)^ in the Midland area is con- 



siderably richer than that of J)^ in the South- Western Province, yet 

 it includes, with very few exceptions, all the species and varieties 

 found in the latter development. 



The chief points in which the coral- faun a of D^ in the 

 Midland area differs from that of D^ in the South-Western Province 

 are as follows : — 



(1) Olisiophyllids belonging to the ' genera ' Histiophyllum, Bhodophyllum, 



and CymatiophyUum occur in abundance. No similar forms have 

 been found in the South-Western Province. 



(2) lAthostrotion junceum is abundant, and L. Martini occurs in con- 



siderable variety and abundance. The typical form of Lithostroiion 

 irregulare is uncommon, but a Lithostroiion which I regard as inter- 

 mediate between that species and L. Martini is characteristically 

 common. In the South-Western Province, the abuadance of 

 L. irregulare characterizes J)^, but L. Martini is comparatively 

 uncommon, and L. junceum is rare. 



(3) Syrioigojwra cf. reticulata is common. This form does not occur in 



Dg in the South-Western Province. 



The distinctive features of the brachiopod-fauna of D^ in 

 the Midland area, as compared with D^ in the South-Western 

 Province, may be summarized as follows : — 



Productus giganteus and its variants occur in great abundance. Pr. semi- 

 reticulatus, Pr. concinnus, and Pr. Martini are abundant. Punctate, scabri- 

 culate, and costate Producii are of frequent occurrence. Productus longispinus 

 and its allies occur not uncommonly. Spirifer bisulcatus and Martinia glabra 

 are abundant, and Spirifer planicosta occurs commonly. Schizophoria 

 resupinata always occurs. 



This statement makes the difference between the brachiopod- 

 fauna of the Midland area and that of the South-Western Province 

 appear very great. It is important, therefore, to note 

 that nearly all the brachiopods here mentioned have 

 been recorded, though rarely, in D.^ of the South- 

 Western Province ; and that certain species, for 

 example Productus concinnus and Martinia glabra., are 

 locally abundant in the South-Western Province. 

 Moreover, in comparing the two developments, it is important to 

 appreciate the impoverishing influence of the conditions which 

 prevailed during Upper Seminula -iime in the South-Western 



Q. J. G. S. No. 253. p 



