﻿218 DR. A. VAUGHAN ON THE TALiEONTOLOGICAL [May 1905, 



The manner in which the same position for these beds has been 

 fixed by stratigraphical reasoning has already been sufficiently 

 described. 



Comparison of the Syringothyris-Zone in the Failand* 

 area with other sections. — It has been sufficiently emphasized 

 that, with the exception of the Belleroj)hon-Beds, there is a complete 

 similarity, both lithological and palaeontological, between the Failand 

 and Avon development of this zone, but that the teller vphon-Beds 

 of the Failand area are represented in the Avon section by unfos- 

 siliferous shales and dolomites. 



The fact that the Seller opTion-Beds are found in a precisely-similar 

 development in the Clevedon area (near Tickenham) illustrates once 

 more the essential similarity of that area with the Failand area. 



Visean. 

 Seminula-iu^ ° (S x & S 2 ). 

 Exposures: 



1(1) Thinly-bedded limestones, immediately above the Bel- 

 lerophon-'Beds in the first and second quarries. 

 (2) Massive limestones, in the small quarry west of Long- 

 wood House. 

 o f (3) Massive limestones, with a thick band of oolite, east of 



2 \ Longwood House. 



Of these: 



(1) and (2) contain Seminida ficoidea and Productus 6 (?), 

 while Lithostrotion is rare or absent. Hence these exposures 

 may be assigned to the base of the Semimda-Zone. 

 (3) contains Productus aff. Cora (mut. S 2 ), Lithostrotion Martini, 

 and Seminida ficoidea in abundance. Hence (3) may be 

 assigned to the middle of the Seminula-Zone. 



Comparison with the Avon section. — As already pointed 

 out, from stratigraphical considerations (2) probably corresponds 

 to the very lowest beds in the Great Quarry, and (3) to the thick 

 oolitic band which occurs near the top of the same quarry, while 

 (1) represents part of the Middle Shales and Dolomites. 



The absence of Caninia cylindrica var. bristolensis in the list of 

 fossils from the lower part of this zone in the Failand area is 

 probably due entirely to the fact that the horizon at which that 

 fossil is abundant in the Avon section is here unexposed. 



Bibunophy Hum-Zone. 

 i. #(/>-subzone (D x ). 



Lithological character. — Massive limestones, with shales 



and some rubbly limestones. 

 Exposure. — Two quarries near Flax-Bourton Station (nearly 



1| miles south, slightly east, of Failand Inn). 



