254 



COMPARATIVE ZOOLOGY. 



Fig. 203.— A strcea pallida ; natural size. Fejee Islands. 



A coral-reef is formed by many Corals growing togeth- 

 er. It is to the single Coral-stock as a forest is to a tree. 



Fig. 2Q4.—Diploria cerebriformis, or "Brain-coral one half natural size. Bermudas. 



