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GENUS I. ACTINOLOBA (Blainv.). 



Actinia (Linn.). 

 Cribrina (Ehrexberg). 

 Sagartia (Gosse). 



Base considerably broader than the column; its 

 outline often undulate, but entire. 



Column pillar-like, in the expanded state; the 

 margin forming a thickened parapet, or low wall, 

 separated from the tentacular disk by a groove or 

 fosse. Surface perfectly smooth, without suckers, 

 but pierced with loop-holes. Substance approaching 

 to pulpy. 



Disk deeply frilled at the margin; thinly mem- 

 branous. 



Tentacles short, slender, not arranged in distin- 

 guishable circles, scattered at their commencement 

 about half-breadth of the disk, becoming gradually 

 smaller, more numerous and densely crowded as they 

 approach the border. 



Mouth surrounded with a thick lip ; furnished with 

 only a single gonidial groove, surmounted by a single 

 pair of tubercles. 



Acontia emitted somewhat reluctantly, but copi- 

 ously upon occasion. 



Only one British species. 



