SEA-FAN MAKERS. 



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fluid ; these are the chambers of the members 

 of the association. The cortex is full of little hard 

 bodies, called spicules (fig. 38). Beneath the crust 

 is the coral, properly so called ; it is as hard 

 as marble, its surface is remarkable for its stripes, 

 its colour is a beautiful red, and it is so hard that 

 it is capable of receiving a high polish. The 



FIG. 38. SPICULES OF RED CORAL. 



polypes are composed of a tubular body, enclosed in 

 a cortical cell. That part which appears beyond the 

 walls of this cell is cylindrical, and is crowned by 

 eight little arms, which spread themselves out like 

 the petals of a flower. These arms are flat and wide 

 at the base, but gradually tapering to a point. The 

 edges are furnished with short hollow barbs. When 

 expanded they are exactly like a beautiful white and 



