﻿Vol. 6 I.] SEQUENCE IN THE BRISTOL AHEA. 257 



Assise II. No fossils cited. 

 Assise III. Orthis resupinata. 



Correlation: Z 2 (lower part). 

 Assise IV. JSpirifer cuspidatus. 



Prof. Dewalque mentions the occurrence of Ampleanis 

 corolloides in the lower part. 

 Correlation: Z 2 (upper part) : y ; lower part of C. 

 Assise V. Large Euompludi. 



Correlation: top of C and S (the BelleropJion-Be&s, in 

 which large Euonipludi are common). 

 Assise VI. Productus Cora and Pr. giganteus. 

 Correlation: S and D. 



It is interesting to note that all the brachiopods mentioned by 

 M. Mourlon and Prof. Dewalque occur in the same order in the 

 Bristol area as in Belgium, and that they are correspondingly 

 characteristic of the beds. 



C. The Parallelism of the Bristol and Belgian Sequence, 

 by Prof. Max. Lohest. 1 



Palaeontologically. — The conclusion that the general resem- 

 blance is complete rests on the occurrence at the same broad levels of 

 the following fossils : — Small PhyncJionellce in M; Sp. tomacensis in 

 K (Prof. Lohest comments on the absence of Spiriferina octoplicata 

 in K, but this is, of course, a mistake); teeth of fishes in Z; Productus 

 Cora and Pr. giganteus in S and D. 



Lithologically. — The writer cites the encrinital character of 

 the Tournaisian, but comments on the absence of cherts from the 

 Upper Tournaisian (ZapJirentis-zone). In the Visean he states 

 that the Avon section is continuously oolitic, and comments on the 

 absence of compact dark limestones. 2 



The amount of similarity expressed by the above facts seems 

 scarcely to warrant his conclusion. 



To sum up the comparison : — Such facts regarding the Belgian 

 sequence as I have been able to quote are in agreement with the 

 sequence as here set out for the Bristol area ; but the fauna is too 

 scanty to allow of close correlation. 



VI. Summary and Analysis, 



The faunal sequence in the Bristol area is summed up in the 

 table of ranges and maxima (pp. 243-247) and in the two range- 

 diagrams (Pis. XXVIII & XXIX, facing pp. 244 & 246). 



These diagrams depict the rise and decline of each species-group, 

 and the .positions at which its mutations are most abundant. To a 



1 Ann. Soc. geol. Belg. vol. xxii (1894-95) Mem. p. 7. 



- The litbological character of the Visean in the Avon section is erroneously 

 described, as^dark compact limestones form there a very characteristic feature 

 of the SemimiTd-Zone. 



