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GENUS I. ZOANTHUS (Cuvier). 



Actinia (Ellis). 



Zoaniha ) 



n 7 ., > (Lamoukoux). 



Zoanthus \ 



Mammilifera > (Lesueuk). 

 Corticifera ) 

 Sidisia (J. E. Gray). 



Base permanently attached ; spreading over rocks, 

 stones, or shells, in either a linear or incrusting 

 manner. 



Column pillar-like, higher than wide; margin cnt 

 into strongly marked teeth, which are united by a 

 thin membrane. Surface smooth, excreting a mucus, 

 in which occasionally grains of sand become imbedded, 

 constituting an adventitious epidermis. 



Bisk slightly concave ; radii inconspicuous. 



Tentacles conical, pointed, similar in structure to 

 those of AsTRiEACEA : wholly retractile. 



Mouth more or less protrusile, simple. 



ANALYSIS OF BRITISH SPECIES. 



Invested with sand ; extension various Couchii. 



Without sand — 



Polypes cylindrical, olive ; several abreast sulcatus. 



Polypes obconic, pellucid white; in single file . . .  . . Alderi. 



