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ANALYSIS OF BRITISH GENERA. 
AYith 'palules : adherent. 
Palules in a single circle : coUimella of many slender 
twisted plates Caryophyllia. 
Palules in several circles : columella broad and irre- 
gular in form Paracyatlius. 
Without palules : free. 
Columella a single plate Splienotrochus. 
Columella absent Ulocyatlius. 
