﻿452 DE. A. TATJGHAN OX THE FATJXAL SUCCESSION [Aug. 1908^ 



Litliostrotion irregulare, Productus giganteus, Pr. latissimus) occur 

 in common association with Posidonomya BecJieri throughout its 

 maximum. 



Elsewhere this fact has seldom been observed, owing to the more 

 complete establishment of Posidonomy a-conditions. 



[The Inter-Relation of the Uppermost Avonian and 

 the Lower Pendleside. 



It has been mv anxious desire in this paper to recognize to the 

 full the large amount of excellent work which Dr. Wheelton Hind 

 has done since the publication of the paper by himself and Mr. J. A. 

 Howe on the ' Pendleside Group ' (Quart. Journ. Geol. Soc. vol. Ivii, 

 1901, p. 347), in further elucidation of that important contribu- 

 tion. With this object in view, I have attempted to commence the 

 P zone at Loughshinny with the lowest level included by him in 

 the Pendleside Series. 



In the report of the Committee on ' Life-Zones in the British 

 Carboniferous Eocks' (Pep. Prit. Assoc. York meeting, 1906, p. 311), 

 Dr. Hind sets out the following subdivisions of the Pendleside 

 Series : — 



Zone of Gastrioceras Listen | ^^Tf Coal-Measures. ^^^onst 



\ Millstone Grit. lioiizona at 



Zone of Glyphioceras hilingue. ^"° ^ ^^^^* 



Zone of Glyphioceras spirale ^ r'l r,- j- i r tt r -d i 



Zone of Gln^hioceras reticulatum ] ^^VP^^oceras diadema. [= Up-^ P.] 



Cyathaxo7iia- j Zone of Posidonomya Becheri . . .Nomismoceras rotiformc . [=Mid. P.] 

 Beds. \ Zone of Prolecanites compressns. Dg. [^L'^P.] 



The lower portion of this table expresses the essential facts of 

 the sequence at Loughshinny. 



The lowest zonal index — Prolecanites compressus — has not been 

 found, but the fauna of Lower P agrees with that which Dr. Hind 

 states to be associated with that index in the Western Midland 

 area {op. cit.). Middle P is a strong maximum of Posidonomya 

 Becheri, and Nomismoceras rotiforme has been recognized by Dr. Hind 

 in our material from that division. Glyphioceras spirale immedi- 

 ately succeeds, and characterizes Upper iP. 



Hence, in the P zone at Loughshinny, we have a typical Pendle- 

 side sequence and the inception of the Upper Carboniferous 

 molluscan fauna of the British Isles. This is reason enough for 

 changing our standard zonal indices at this point, from those marking 

 moderate depth to those indicating shallow water. 



At Loughshinny, however, a CyatJuLvonia-ia-unsi is intercalated 

 in the Posidonoriiya-m.a.xim\im. and persists up to the zone of 

 Glyphioceras spirale. This fauna is in perfect continuity with that 

 of the Oyathaxonia-^ediS below (Dsq., Dgj) and contains a large 

 number of typical Avonian forms. We must, therefore, recognize 

 that the Lower Pendleside and the Uppermost Avonian are the 

 expressions of contemporaneous faunas. — May SOih, 1908.^ 



