CERITHIIN^. 283 



ivray being founded on a young Buccimim. Neither the 

 animal nor operculum are known, but fi'om the circum- 

 stance of the surface of the recent and fossil shells 

 being sometimes partly covered by Corallines, and the 

 fossil species occurring with marine shells, it is doubt- 

 less an inhabitant of the sea, and has even been stated 

 once to have been procured from the Bay of Naples ; 

 the position of the genus in a natural system is, how- 

 ever, difficult to determine until the animal is known; 

 the shell has been called an Achatina, a Bulla, a Buc- 

 cinum, and a BuUmus. 



Fam. CERITHIID^. 



Lingual membrane long and linear, armed with a 

 single series of median teeth, and three lateral series of 

 hooked, multicuspid uncini (3'1'3) ; outer lateral teeth 

 conical, curved. Rostrum broad and short; tentacles 

 wide apart, subulate ; eyes on short pedicels united to 

 the outer sides of the tentacles. Mantle-margin with a 

 rudimentary siphonal fold in front ; gill composed of a 

 single series of plates. Foot broad and short, angulated 

 in front. 



Operculum horny, spiral or subspiral. 



Shell spiral, many-whorled ; aperture more or less 

 channelled in front ; outer lip often expanded in the 

 adult. 



Sub-fam. CERITHIIN^. 



Operculum ovate or semicircular, of few, rapidly-en- 

 larging whorls. 



