102 



GOBALS AND CORAL ISLANDS. 



The Hydra is the type of a large group of species. It buds, 

 but the buds drop off soon, and hence its compound groups 

 are always small, and usually it is single. But other kinds 



PLUMULARIA FALCATA. 



multiply by buds that are persistent, and almost indefinitely so ; 

 and they thus make membranous coralla of considerable size 

 and often of much beauty. 



