341 



FAMILY VI.— EUPSAMMIADiE. 



The stony tissue is here deposited in such a manner that 

 the corallum, instead of being compact, is porous, but not 

 so open as to have a spongy texture. The wall is thick, 

 and constitutes the chief part of the whole ; it is perforate, 

 and either almost or quite naked, with a granulate ver- 

 miculate surface. 



The plates are numerous ; those of the last cycle always 

 deviate from the radius of the calice, their planes approach- 

 ing the bisection of their system, so that the whole septal 

 arrangement assumes the form of a six- or twelve-rayed 

 star; by which very remarkable peculiarity this family 

 may be infallibly recognised. The plates are perforate. 

 The interseptal chambers are completely open to the bottom, 

 or divided only by a few incomplete partitions. 



There is only one British genus known, BalanopJiyllia. 



