Fig. 12 Transverse section of polypary of 



Coppinia arcta for correlation with crust of 



Hydractinia (Fig. 7), and tho section of stem 



of Antennularia (Fig. 13). 



(a). Zoophyte stem, upon which Coppinia arcta is parasitic. 



(b). Horizontal cells or tubes (?), from which arise the 

 vertical tubes c. 



(c). Vertical polypite tubes. 



