﻿Vol. 6l.] SEQUENCE IN THE BEISTOL AREA. 223 



below the massive limestone (2), would have been easily eaten 

 back at the base of the ancient cliff, leaving an overhanging wall 

 formed by the lowest beds of (2). The subsequent infilling of this 

 recess by Dolomitic Conglomerate would exactly produce the 

 phenomenon described. 



Fauna : — 



Product us aff. Coramut. G, Pr. 0, J Liihostrotion Martini & varieties, 

 and Pr. aff. semireticulatus. Caninia sp. 



Seminula ficoidea and allied j Syrijigothyris aff. laminosa (?) . 

 forms. ) 



Notes. — Liihostrotion is rare at the base, but becomes very abundant at 

 the top. Caninia was determined from rather unsatisfactory sections 

 seen in situ just below the beds of sandstone. Syringothyris aff. lami- 

 nosa (?) is merely a suggested correction of ' Bpirifera octoplicata,' 

 which is recorded by the Eev. H. H. Winwood from the lower sand- 

 stone-bed. 



The presence of Productus aff. semireticulatus and of Caninia, 

 the rarity of Liihostrotion in the lowest beds and its increasing 

 abundance above, together with the presence of a Spiriferid of the 

 laminosa-type, seem to me to afford sufficient evidence for assigning 

 these beds to S,. 



Upper Seminida-Zoue (S 2 ). 



The upper part of the large quarry may be referred with the 

 greatest probability to the middle of the Semi?mla-Zone. As is 

 usual in other sections at this level, there is a thick band of 

 fossiliferous oolite. 



Fauna : — 



Seminula ficoidea and allied forms, j Liihostrotion Martini. 

 Productus aff. Cora. Syringopora sp. 



Productus aff. hemisphericus. Clisiophyllid (rare). 



Chonetes papilionacea. 



The quarry north of the railway, near the station, contains the 

 same fossils, and is also undoubtedly in the Seminula-Zone. 



Comparison of the Tytherington Section with those 

 of the Avon, Sodbury, and Failand. 



I. Characters common to all four sections. 



(1) The fauna of Horizon a (the ' Bryozoa-Bed ') is iden- 



tical. 



(2) Ortkotetes crenistria (in its mutations) is predominant 

 throughout the Tournaisian, but becomes extremely 

 scarce in higher beds. 



(3) Spirifer aff. daihratus reaches its maximum (at which 

 point it is enormously abundant) and declines, before 

 Oliothyris glabristria and Schizophoria resupinata 

 attain their maxima. 



(4) Schizophoria resupinata and Oliothyris glabristria reach 



a maximum together, and both are very abundant at 

 this point. 



