40 



II. Head scarcely exposed; tentacle short ; eyes none; foot elon- 



gate, dilated in front {one-coloured). Shell, sutural groove 

 open. 



7. Anazola. 



Shell subcylindrical or subovate ; aperture oblong, thickened ; 

 front belt broad, double. 



8. Agaronia. 



Shell subovate ; aperture ovate ; pillar slightly thickened ; front 

 belt single, moderate. 



III. Head hidden; tentacles none; eyes none; foot short, very 

 broad, rounded on the sides, one-coloured ; opercida distinct. 



9. Olivina. 



Spire conical ; sutural groove open to the apex ; aperture of shell 

 moderate ; operculum distinct ; foot very short, front lobes linear. 



10. SCAPHULA. 



Spire conical ; sutural groove open to the apex ; aperture of shell 

 wide ; pillar lip thick, smooth, with two grooves in front ; opercu- 

 lum none ? ; foot large, front lobes very large, rounded. 



11. MlCANA. 



Spire callous ; sutural groove only open on the last whorls ; aper- 

 ture moderate ; operculum distinct. 



1. Strephona. 



Shell subcylindrical ; spire conical or flattish, small ; aperture 

 linear ; pillar lip simple, only expanded in front, and not covering 

 the callus ; front belt narrow ; inner lip cross-grooved. Foot elon- 

 gate, longer than the shell, broad, rounded behind, dilated on the 

 sides, which are bent up and cover the shell, the front lobes nearly 

 semicircular, rather produced and acute at the hinder outer angles. 

 Head exposed ; tentacles elongate ; eyes one-third from the base ; 

 operculum none. 



Adanson, in his ' Hist. Nat. du Senegal,' regards all the speci- 

 mens of this genus as belonging to one species, observing : — "La 

 couleur de cette coquille est peu constante. J'en ai de blanches, de 

 jaunes, de jaunes livids, de jaunes verd, &c, raeme de verdatres sans 

 aucun melange. J'en ai aussi qui, sur ces differens fonds, sont taches, 

 tigrees, marbrees ou couvertes de zigzags, qui s'etendent tantot sur 

 leur longueur, tantot sur leur largeur. Ces taches, ces points, ces 

 bandes, et ces lignes sont cendres, noir ou bleuatre dans les unes, 

 brun, rougeatres ou pourpres dans les autres : enfin leur melange 

 est si varie, que ce seroit perdre son terns que de faire F enumeration 

 de toutes celles qui ont e'te' de'ciites ou figurees par leurs auteurs. Je 



