THE CARBONIFEROUS LIMESTONE OF BURRINGTON COMBE 23 
Michelinia cf. favosa. 
Syringopora 9. 
Brachiopod fauna. 
Cliothyris Royssii (mut. ^). 
Cliothyris glabristria. 
Spirifer afP. clathratus and var. 
Reticularia aff. lineata. 
Martinia glabra., var. linguifera. 
Syringothyris aff. cuspidata. 
Syringothyris cuspidata. 
Syringothyris aff. laminosd. 
Leptaena analoga. 
Orthotctcs aff. crmistria. 
Rhipidomella aff. Michelini. 
Schizophoria resupinata. 
Chonetes cf. hardrensis 
Chonetes aff. papilionacea 
Chonetes papilionacea'. 
Productus cf. Martini 
Productus semireticulatus J 
Productus pustulosus. 
Productus aff. Cora. 
and intermediate 
mutations. 
and intermediate 
mutations. 
The base of this zone has been fixed at the point where 
Zaphrentis is first recorded. 
In the Bristol Area, as typified by the Avon Section, 
the base of this zone is characterized by the co-occurrence 
of Zaphrentis and Spiriferina octoplicata, and thus exhibits 
a well-marked overlap of the Cleistopora and Zaphrentis 
faunas = Horizon 8. 
At Burrington, however, Spiriferina octoplicata is rare 
throughout the Cleistopora Zone and has not been found 
in association with Zaphrentis. Horizon /3 cannot, there- 
fore, be distinguished ; and accordingly all beds below 
the level at which Zaphrentis first appears are included 
