78 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



is also globular ; but the mouths of the polyps open into 

 each other, forming furrows. Fungia, or " mushroom 

 coral," is disk-shaped, and differs from other kinds in 



FIG. 29. Ctenactis ecktnata, or " Mushroom Coral " : one fourth natural size. Pacific. 



being the secretion of a single gigantic polyp, and in 

 not being fixed. Madrepora is neatly branched, with 



FIG. 30. A strcea pallida, living colony; natural size. Fejee Islands. 



pointed extremities, each ending in a small cell about 

 a line in diameter. Porites, or "sponge coral," is also 

 branching, but the ends are blunt, and the surface com- 



