36 THE CARBONIFEROUS LIMESTONE OF BURRINGTON COMBE 
D. Seminula Zone. 
This zone includes all that part of the section lying 
between the top of Horizon S, at Plumley’s Den, and the 
middle of the limekiln quarry. 
Lithological characters. 
Chiefly massive limestones, oolitic in parts ; with con- 
cretionary limestones near the top, and very compact 
limestones at the top of the zone. 
Exposure. 
The basal beds are poorly exposed between Plumley’s 
Den and the quarry at the side of the road. Beyond this 
quarry, on the grassy slope at the side of the lane leading 
to the limekiln quarry, the beds are poorly exposed at 
intervals. The top beds of the zone are exposed in the 
limekiln quarry. 
Coral fauna. 
Lithostrotion Martini and vars. 
Cyathophyllum Murchisoni. 
‘ Clisiophyllum ’ (Carcinophyllum) 0. 
(?) Dihunophyllum B. 
Syringopora spp. 
Brachiopod fauna. 
Seminula ficoidea and vars. 
Athyris aff. planosulcata (?) 
Orthotetes aff. crenistria. 
Productus 0. 
Productus afl. Cora (muts.) 
Productus hemisphericus. 
Chonetes papilionacea. 
No subdivision of this zone is justifiable. The lower 
part of the zone differs from the upper only in the pre^ 
