LAND AND FRESH-WATER SHELLS 



NORTH AMERICA. 



11. 



PULMONATA. 



Suborder LIMNOPHILA. 



Eyes sessile ; tentacles subcylindrical or flattened, simply eon- 

 tractile. Operculum wanting. Animal usually lacustrine or 

 fluviatile, sometimes marine or littoral, rarely terrestrial. 



All the known families of Limnophila are represented in this 

 country. Their habits are described under each. 



Family AURICULID^. 



Lingual membrane broad and elongated ; teeth numerous, 

 in slightly bent, cross series ; central tooth equilateral ; lateral 



Lingual dentition of Alexia myosotis. 



•teeth rather inequilateral, diminishing in size towards the 

 outer edge. Head ending in a snout ; mouth with a horny 

 lunate upper jaw,' and with two dilated buccal lobes, united 



' See Alexia myosotis, p. 4. 



( 1 ) 



