92 



POPULAR CONCHOLOGY. 



row, right lip having a thick margin ; plaits 

 on the columella lip nearly equal in size; 

 no operculum. Animal, with large, usually 

 papillose mantle lobes, reflected over the 

 shell and over the spire ; head somewhat 

 muzzle-shaped ; mouth with a retractile pro- 

 boscis; tongue constructed like that of Cy- 

 prcea ; tentacles subulate, bearing eyes on 

 bulgings at their external bases ; siphon pro- 

 duced ; foot large, truncated in front, ob- 

 tuse behind.* — 108 species f ; also fossil. 



These shells are often very beautifully polished and 

 coloured; many have the spire exceedingly short. The 

 inhabitant covers the shell with its mantle, depositing suc- 

 cessive layers of shelly matter, for it is found that the 

 specimens of this genus differ materially in thickness of 

 substance. The species are found in the tropics. 



Family 10. — CORIO CELL A CEA. 



The animals have a half globular mantle, which encloses 

 the body and the thin inner shell : the head has two long- 

 remote tentacula, with the eyes at the outer base. Shell 

 thin, transparent, ear-shaped, with a few quickly increas- 

 ing whorls ; the aperture very large and entire. 



Marsenia. Leach. (Coriocclla Blain ; Sigaretus Cu- 

 vier, not Lam. ; Cryptothyra Menhe ; Cheli- 

 notus Sw.; Lamellaria Gray ; Oxynoe Couth.) 

 — Shell thin, milky white, somewhat car- 

 shaped; spire depressed, very small : body whorl 

 very large; aperture large and entire; opercu- uanaua. 

 lum none. Animal, with the mantle entirely 

 investing the shell, emarginate in front; head rather broad. 



; Forbes's British Moll. 



t Sowerby's Thesaurus. 



