118 
THE AVONIAN OP THE AVON GORGE 
Brachiopods : — 
Productus giganteus. 
Prod.hemispherictis. I abundant. 
Prod, corrugato- | 
hemis'phericus. 
Chonetes [Daviesiella) aff. comoides. 
Orthothetids, especially Derby a 
(rare, except locally e.g. at 
Westbury). 
Cyrtina septosa (rare, except 
locally e.g. at Lydstep). 
Local detail : — 
^ TrTT» This siibzone can be examined in the rail-side 
Plate VIII. . , 
exposure immediately south of the level-crossing, at 
the bottom of the new Zig-zag ; it is, however, best studied 
in the very numerous exposures of bare rock on the slope 
north of that path. (The New Zig-zag should be ascended until 
the steepest portion has been surmounted and the slope on 
the left-hand side should then be climbed as far as the edge 
of the cliff section.) 
In the repetition of the series, south of the Great Fault, the 
fossils characteristic of the Di subzone can be readily recognized 
in the rock-face between the Colonnade and the foot of the 
Old Zig-zag, as well as in the exposures by the side of that 
path. (The Old Zig-zag path practically follow^, a dip-slope 
and consequently the level of the beds which are exposed at 
the side continues to be approximately the same, from bottom 
to top.) 
Cyrtina seytosa and Derby a have not yet been recognized on 
either side of the Avon Section. 
D2 = Subzone of Lonsdalia floriformis. 
Diagnosis : — 
The presence of highly specialized Clisiophyllids, (such as 
Lonsdalia, and Dihuno'phylla of the type of Dih. ij/.). 
The entrance of compound Cyaihofliylla, and the importance 
of the Martinia section of the Spiriferids. 
