GASTEROPODA. 125 



Listr., 4 sp. Britaiiij Norway, N. America, Icy sea to Kamtschatka. 

 Living on stones near low water, and ranging to 30 fms. 



Fossil, 3 sp. Miocene — . Brit. 



Sub-gemcs. Oiina (Gray). V. otis. /S7/^/^ minute, ear shaped. Animal 

 like velutina, but with a simple mantle, and veiy short tentacles. W. and 

 S. W. Brit, coast ; inhabiting chinks of rocks, between tide-marks (Forbes). 



FAMILY II. Ptramidellid^. 



S/iell spiral, turreted ; nucleus minute, sinistral ; aperture small ; columella 

 sometimes with one or more prominent plaits. Operculum horny, imbricated, 

 uuchs internal. 



Animal with broad ear-shaped tentacles, often connate ; eyes behind the 

 tentacles, at their bases ; proboscis retractile ; foot truncated in front ; ton- 

 gue unarmed. Species all marine. 



Several genera of fossil shells are pro\asionally placed in this order, from 

 their resemblance to euliyna and cJiemnitzia.* TornateUa, usually placed in or 

 near this family, is opistho-brancJiiate. 



Pyeamidella, Lam. 



Etym., dimunitive of pyramis, a pyramid. 



Syn., obeKscus, Humph. (P. dolabrata. PI. VIII., fig. 11.) 



Type, P. aui-is-cati. PI. VIII., fig. 10. 



Shell slender, pointed, with numerous plaited or level whirls ; apes sinis- 

 tral ; colmnella with several plaits ; lip sometimes furrowed internally. Operc. 

 indented on the inner side to adapt it to the columellar plaits. The shell of 

 the typical pyramideUse bears some resemblance to cancellaria. 



Bistr., 11 sp. "W. Indies, Mauritius, Australia. 



Jb^«/, 12sp. Chalk?—. Fi-ance, Brit. 



Odostomia, Fleming, 1824. 



Etym., odozis, a tooth, and stoma, mouth. 



Type, 0. plicata, PI. VIIL, fig. 12. 



Shell subulate or ovate, smooth ; apex sinistral ; apertm'e ovate ; peristome 

 not continuous ; columella with a single tooth-like fold ; lip thin ; opercvdum 

 homy, indented on the inner side. 



Di3tr., sp. Brit., Medit., Red Sea, Australia. 



Fossil, 15 sp.? Eocene — . Brit., France. 



Very minute and smooth shells, having the habit of rissoce, and like them 

 sometimes found in brackish water. They range from low water to 40 fms. 

 The animal is undistinguishable from chemnitzia. 



* "The Pyramidellidce present subjects of much interest to the student of extinct 

 moUusca; numerous forms, bearing all the aspect of being members of this family, 

 occur among the fossils of even the oldest stratified rocks. Many of them are gigantic 

 compared with existing species, and the group, as a whole, may be regarded, rather 

 as appertaining to past ages than the present epoch." (Forbes.) 



