SUBDIVISIONS OF ACTINOID POLYPS. 



70 



of the larger kinds of simple corals, such as those of the gen- 

 era Zaphrentis and Heliophyllum, had at times a diameter of 



PORITES LEVIS, D. 



three or four inches, so that the breadth of the polyp flower 

 was probably at least six inches. Hemispherical masses of 



