PYRAMIDELLAD^. 



123 



Cerithmm (Bmg.). Shell very long, tapering, 

 pointed ; aperture small, witli a tortuous canal ; 

 outer lip expanded ; inner lip thickened ; oper- 

 culum spiral, few-whorled. 



C. adversum. 

 reticulatum. 

 metula. 



Fig. 188 ; f . 



187 



189 



188 



Cerithiopsis (Forbes). Shell as Cerithium; 

 operculum pointed. 



C. tubercularis. Fig. 189 ; f. 



Family XI. Pyramidellad^. 



Shell spiral, generally lengthened, pointed; aper- 

 ture small ; pillar often plaited ; operculum formed 

 of overlapping plates ; animal with broad, ear- 

 like tentacles, and eyes behind them; proboscis 

 retractile; foot truncated in front; tongue un- 

 armed. 



