THE POLYPIERS. 99 
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siliceous grains (spiculze) that it remains in the form of a crust when 
they are dried. This crust is crumbly, and often preserves the 
brilliant colours which characterise this polypier. Their cells are 
hollow, sometimes indented in an even surface, sometimes they pro- 
duce mamillary risings. They are generally smooth, though they 
are found sometimes rough and shelly, and drooping one over the 
AN ALCYONIDA. 
(Xenta elongata.) 
other. The /szs and the Coral belong to this group, and all those 
black, smooth, and flexible tree-like growths which we find on our 
coasts, to whose consideration we shall devote the following chapter. 
Side by side with the Gorgons, M. Deshayes has placed the beau- 
tiful parasite polypier found at Calle—the A xthozoanthus—a mag- 
nificent upright shrub, with an axis of a dark brown, the cortex of 
a bright, delicate rose colour, and polypes of a golden yellow. 
The polypiers are fixed to solid bodies ; sometimes they attach 
themselves one to another, hooked on and interlaced in every 
direction. Some of them are whitish, others quite white, some 
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