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THE AVONIAN OP THE AVON aOli(JE 
Cam'po^Jiyllum. 
Coralliim cylindro- conical, with thick, annulated epi theca. 
Central area tabular and free from septa. 
Medial area occupied by a ring of equal primary septa which 
are attached to the tabulae. 
Outer area vesicular and either devoid of radial structure, 
or radiated, more or less perfectly, by thin septal prolongations 
of both series of septa. 
Septal break inconspicuous. 
Fossula undeveloped in typical examples. 
Tabulae broad and flat, and stretching completely across the 
central and medial areas. 
Secondary septa short. 
The essential characters of this genus are : — 
(1) Broad, flat tabulae. 
(2) No fossula. 
(3) A uniform ring of primary septa which do not reach the 
centre, 
