lil-CCINULUS. o 



provided with but a single plait. Several species have 

 been described from Equatorial Seas, and one, the Voluta 

 tornatilis of Linnaeus, is an inhabitant of the Mediterra- 

 nean and of the British Islands. Many fossil shells 

 occur in the Secondary and Tertiary formations which 

 appear to belong to this genus. 



Species of Aetceon. 



Bevaletii, Baudon. pudicus, A. Adams. 



Cumingii, A. Adams. puncto-striatus, Couth. 



Diana?, A. Adams. Senegalensis, Petit. 



flammeus, Gmel. Sieboldii, Reeve. 



Maria?, A. Adams. tornatilis, Linn. 



rnodestus, A. Adams. venustus, D'Orb. 



oryza, Beer,'. virgatus, Reeve. 



Genus BTJCCINULUS, Plancus. 



Shell thick, solid, ovate, transversely sulcate ; spire 

 elevated, acute ; aperture longitudinal, narrow, entire and 

 rounded anteriorly; inner lip thickened, callous; colu- 

 mella with two spiral plaits, the anterior grooved and 

 continued into the outer lip. 



Syn. Pupa, Bolt., not Humph. Solidula, Fischer. 

 Dactylus, Sckum., not Klein. 



Ex. B. solidulus, Linnteus,\)\. 56, fig. 2, 2, a. Oper- 

 culum, B. solidulus, fig. 2, b, 2, c. Shell, B. solidu- 

 lus, 2, d. 



The principal characters which seem to separate this 

 genus from Action, consist in the solid structure of the 

 shell, and in the double spiral fold of the columella. In 

 the allied fossil genus Actaonella the aperture is poste- 

 riorly canaliculated, and there are three large folds on the 



VOL. II. C 



