THE AVONIAN OF THE AVON GORGE 
109 
Rhifidomella ail. Michelini reaches its maximum near 
the top of Zi and specimens should be looked for on the 
surfaces on which Chonetes cf. hardrensis is abundant. 
= Subzone of Zaphrentis aif. cornucojpiae. 
Diagnosis : — 
The association of Zaphrentis aff. cornucopiae with Zaph- 
rentis aff. Phillipsiy the rarity of Caninia, and the gradual 
decline of the Zi Brachiopod-fauna. 
The lower part of the subzone is marked by the entrance of 
Schizophoria aff. resupinata and by the abundance of Athyris 
aff. glabristria ; the upper part is characterized by the great 
abundance of the two species of Zaphrentis, and by the entrance 
of Caninia and of the large form of Syringothyris aff. cuspidata 
which is so important a fossil of the Syringothyris -Zone. 
Fauna : — 
Corals : 
ZayTirentis aff. cornucopiae. 
Zayh. aff. PJiilli'psi, 
Brachiopods : 
Productus cf. hurlingtonensis. 
Prod. aff. semireticulatus. 
Chonetes cf. hardrensis. 
Papilionaceous Chonetes. 
Orthothetes cf. crenistria. 
Amplexus cf. coralloides. 
Syringopora 6. 
Michelinia, spp. 
Schizophoria aff. resupinata. 
Phipidomella aff. Michelini. 
Syringothyris aff. cuspidata. 
Syringothyris cf. laminosa. 
Athyris aff. glabristria. 
Bryozoa, Crinoids and Palechinus. 
Elasmobranchs : 
Psammodus, Orodus, Helodus, etc. 
Localdetail: — 
Within the main Black-Bock Quarry, namely that 
portion which lies south of the broad dip slope 
below the cave, the whole of the Z2 subzone is comprised. 
The ‘ Fish Beds ’ occur about the middle of the subzone and 
separate two rather distinct faunal assemblages. (It is not 
Plate III. 
