QA4 COMPARATIVE ZOOLOGY. 
Fre. 197.—Madrepora aspera, living and expanded; natural size. Pacific. 
being fixed. /adrepore is neatly branched with pointed 
extremities, each ending in a small cell about a line in 
diameter. Pordtes, or “Sponge-coral,” is also branching, 
but the ends are blunt, and the surface comparatively 
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Fig. 198.—Ctenaetis echinata, or “* Mushroom-coral ;” one-fourth natural size. Pacific. 
