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GENUS V. ARACHNACTIS (Sars). 



Column moderately long, cylindrical, rounded at 

 the inferior extremity, but not swollen, imperforate. 

 Surface capable of temporary adhesion, and therefore 

 probably studded with minute suckers. 



Disk ? 



Tentacles of two kinds, the one marginal, very long, 

 slender ; the other gular, short ; few in each series, not 

 retractile. 



Mouth, a simple slit. 



Habit: freely swimming in the sea, 



There is but one British species, A. albida. 



