19G 



TEE BOTTOM OF THE SEA. 



clivisious of the fissures or cells harden gradually, 

 owing to the deposit of calcareous matter in the 

 interior of their tissue. It forms little transverse 

 plates, which close the bottom of the cells, bounded 

 by the radiating divisions. When the polyp dies, 

 we discover at the bottom of the place which it oc- 

 cupied a stony polypier, divided by plates which 

 converge towards an axis, and terminate at the upper 

 extremity by forming a little starry cup (fig. 36). 



Fiir. 30. — Dendrophyllia Uamea. 



1. Katuial size, with polyps. 



2. Magnified, with tlie polyps dead. 



The differenie between the various polypi of this 

 gn up consists especially in their mole of reprc- 



