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GENUS III. ADAMSIA (Forbes). 



Medusa^ (Bohadsch). 

 Actinia (Adams). 

 Cribrina (Ehrenb.). 



Base adhering to the inner lip of univalve shells ; 

 greatly expanded laterally in two wing-like lobes, 

 which, gradually advancing on each side, at length 

 surround the mouth of the shell, and meet on the 

 outer side of the body-whorl. 



Column greatly depressed ; margin forming a low 

 sharp parapet, with a distinct fosse. Surface smooth 

 towards the summit, striated or irregularly furrowed 

 on the outer (= lower) part ; pierced with loopholes, 

 which, on the outer (= lower) part, form permanent 

 warts. Substance fleshy. 



Bisk, long-oval, almost linear, smooth. 



Tentacles numerous, sub-marginal, short, crowded, 

 imperfectly retractile. 



Mouth protrusile, large, thrown into loose folds, but 

 not furrowed. 



Acontia emitted freely and copiously. 



The genus contains but one known species, A. pal- 

 liata. 



