18 THE CARBONIFEROUS LIMESTONE OF BURRINGTON COMBE 
II. DETAILED ACCOUNT OF THE BURRINGTON 
SECTION. 
A. Cleistopora Zone (including Modiola Shales). 
Lithological characters. 
This zone includes the whole of the thick series of shales 
and limestones which lies between the top of the Old Red 
Sandstone and the base of the Zaphrentis Zone. 
[As is explained in the sequel, a separation of the lower 
part of this series as a Modiola Zone would not agree with 
the evidence. The whole series is, therefore, included 
in the Cleistopora Zone.] 
Exposure. 
The beds are exposed in the ravines, formed by the 
“ Twin Streams,” which furrow the north slope of Black- 
down and open out into the Combe. They are best ex- 
amined in the east ravine. 
Coral fauna. None as yet recorded. 
Brachiopod fauna. 
Cliothyris Royssii (vars.) 
Eumetria sp. 
Cliothyris glahristria. 
Camarotoechia mitcheldeansis . 
Spirifer aff. clathratus, and var. 
Syringothyris aff. cuspidata. 
Spiriferina octoplicata. 
Orthotetes aff. crenistria. 
Rhipidomella ah. Michelini. 
Productus cf. hassus. 
Productus cf. Martini. 
Chonetes cf. hardrensis. 
Chonetes ‘ Buchiana ’ [Dav.] 
Special faunal characters. • 
In the lower part of the zone, the shales contain Modiola 
