PYRAMIDELLAD^S. 



123 



Cerithium (Brug.). Shell very long, tapering, 

 pointed ; aperture small, with a tortuous canal ; 

 outer lip expanded ; inner lip thickened ; oper- 

 culum spiral, few-whorled. 



C. adversum. 

 reticulatum. 

 metula. 



Fig. 188 ; f . 



188 



CeritJiiopsis (Forbes). Shell as Cerithium; 

 operculum pointed. 



C. tubercularis. Fig. 189 ; f . 



FAMILY XI. PYRAMIDELLAD^E. 



Shell spiral, generally lengthened, pointed; aper- 

 ture small ; pillar often plaited ; operculum formed 

 of overlapping plates ; animal with Ibroad, ear- 

 like tentacles, and eyes behind them; proboscis 

 retractile ; foot truncated in front ; tongue un- 

 armed. 



