Living Lights that Never Die 289 



brain corals, branched corals), but instead they some- 

 times form their framework of a more flexible material, 

 the chief constituent of which is chitin, the horny sub- 

 stance that composes the wing cases and hard parts of 

 beetles and many other insects. 



gorgonia; a sea fan. 



On the mud flats and coral reefs of Florida, and the 

 reefs that form the keys, can be seen the sea fans grow- 

 ing in vast fields, strange, exotic, and colorful. Tech- 

 nically they are known as Gorgonias. They are col- 

 onies of polyps having a calcareous or horny skeleton 

 branching profusely in one plane. The branches are 

 often fine and run together, forming a network of great 

 intricacy. Some of these structures are several feet in 

 length and in breadth, and are in the shape of an enor- 

 mous fan. Certain varieties of Gorgonias resemble 

 branching shrubs; and the shapes of others are rodlike, 



