106 
THE AVONIAN OF THE AVON GORGE 
Crinoids : 
Three or four species are represented by fragments which build up 
the greater part of the limestones, but their identification awaits 
further work. 
Local detail : 
j As already remarked, the exposures in this sub- 
zone are very poor and search must be made wher- 
ever a bare patch of rock can be seen. The surfaces of many of 
the thin limestones are covered with Bryozoans, beautifully 
weathered out. 
A special search should be made for the zonal and subzonal 
indices, Cleisto'pora cf . geometrica and Sfiriferina cf . octoplicata, 
at the side of the line just noiTh of Press’ Quarry ; good speci- 
mens of both fossils have been obtained from this level. 
The Brachiopods above cited are abundant in the thin 
limestones throughout the subzone and, near the top, the Spiri- 
ferids form the dominant feature of the fauna. 
The characteristic Ki forms, such as Productus bassus and 
Eumetria aff . carhonaria, have not, as yet, been recorded from 
this sub zone in the Avon. On the other hand, the charac- 
teristic JjowQT-Zaphrentis Brachiopods (such as Productus cf. 
hurling tonensis, Athyris aff. glabristria, Athyris Royssii mut. /3, 
Reticular ia cf. reticulata and Rhifidomella aff. Michelini) be- 
come more and more abundant as we approach the top of the 
Cleistopora- Zone . 
Zaphrentis -ZojiQ : Z = 
Zonal index : — Zaphrentis aff. PJiillipsi. 
Diagnosis : — 
At the base, Zaphrentis enters and Cleistopora has become 
extinct. 
At the top, Caninia becomes abundant. 
Z2 
Zi 
