26 THE CARBONIFEROUS LIMESTONE OF BURRINGTON COMBE 
maxima of Zaphrentis aff. Phillipsi, Zaphrentis aff, cornucopiae^ 
Syringopora d, Gliothyris glahristria and Schizophoria resupinata 
are not, therefore, capable of accurate determination. 
(iii) Horizon y. 
Since the corals and brachiopods characteristic of both 
the Zaphrentis and Syringothyris Zones co-occur here in 
abundance, this level forms a well-marked horizon of 
faunal overlap. The beds are extremely fossiliferous and 
are, from the collector’s point of view, the most interesting 
in the section. Further, this level is remarkable for the 
association of Caninia cylindrica, in great abundance, with 
an abundant brachiopod fauna which, in the Bristol area, 
characterises the lower resupinata sub-zone. These fea- 
tures are clearly brought out by the following list of : — 
Special faunal characters. 
Brachiopods. 
Gliothyris glahristria occurs, but is uncommon. 
Spirifer aff. clathratus and var. are still abundant. 
Syringothyris cuspidata, in the t3rpical form characteristic 
of the succeeding zone, is common. 
Schizophoria resupinata occurs commonly. 
' Leptaena analoga occurs here, but has not been recorded 
from any higher level. 
Chonetes cf. hardrensis and Chonetes aff. papilionacea 
occur commonly. 
Orthotetes aff. crenistria and Chonetes papilionacea are 
abundant. 
Productus semireticulatus in its typical form occurs not 
uncommonly at this horizon. 
Productus pustulosus has been found at this level only. 
Corals. 
Caninia cylindrica attains its maximum, and is extremely 
abundant. 
Zaphrentis aff. Phillipsi and Zaphrentis aff. cornuco- 
piae are abundant. 
