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ANALYSIS OF BRITISH GENERA. 



With palules : adherent. 



Pahdes in a single circle : columella of many slender 



twisted plates Caryophyllia. 



Palules in several circles : columella broad and irre- 

 gular in form Paracyathus. 



Without palules : free. 



Columella a single plate SphenotrocTms, 



Columella absent Ulocyathus. 



