480 



RADIATA: POLYPI. 



in multiples of six. Those of this group which are called 

 Mseandrinas, have the surface covered with winding 



FIG. 729. 



FIG. 727. 



FIG. 728. 



Merulina speciosa, Dana. Oculina Iwrrescens, 



Dana. 



Astrcea pallida, Daria. Portion of 

 large dome, alive. 



trenches (Fig. 726), on each side of which there is a row 

 of tentacles. The form of the Maeandrinas is generally 

 hemispherical, and some of these masses are twelve feet 



FIG. 730 



Dana's Astrangia, Astrangia Dance, Agassiz. 



in diameter. The true Astrseans, or Star Corals (Fig. 729), 

 have the cells in the form of concave pits, and the com- 



