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COMPARATIVE ZOOLOGY. 
Fig. 203.— Astrcea 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. 204 .—Diploria cerebriformis , or “Brain-coralone half natural size. Bermudas. 
