44 POPULAR CONCHOLOGY. 



ing the whole of the body, two at 

 the sides of the aperture, the others 

 on the back. They are enclosed in a 

 membranous bag, a continuation of 

 which forms the peduncle. Animal 

 rather compressed, peduncle thick. — 

 1 recent species. 



This genus is found near the coasts of Se- 

 negal, and also in the Northern Seas. It attaches 

 itself to buildings covered by the sea. 



23. Otion. Shell composed of 

 five small testaceous valves, adher- 

 ing near the sides of the aperture, 

 enclosed in a membranous bag, 

 but terminating in two tubes at 

 the back ; the centre aperture ad- 

 mits the passage of the tentacula. 

 — 4 species. 



Found in similar situations to the last genus. 



