GENERA OF SHELLS. 67 



AURICULA. Shell sub-oval or ovate oblong ; 

 aperture longer than broad, very entire at 

 base, narrowing upwards where its margins 

 are disunited, columella with one or more 

 plaits. Lip with the margin sometimes re- 

 flected, sometimes simple and sharp. 



Land shells, and distinguished from bulimus by the 

 folds on the columella. 



(a.) Shells with the margin reflected outwards. 

 A. auris-midae, a. Judae, a. Sileni, a. leporis, a. Gelis, scara- 

 bseus, bovina, caprella, myosotis, minima. 



(&.) Shells with the margin simple and acute. 

 A. Dombeiana, coniformis, nitens, monile. 



CYCLOSTOMA. Shape of shell variable ; 

 whorls cylindrical, aperture circular, regular ; 

 margins continuous, dilated or reflected by 

 age. An operculum. 



Land shells, never pearly, generally thin, and with- 

 out scales or tubercles on the outside ; distinguished 

 from the paludina by the outward reflection of the 

 margin of the adult shell ; whilst in paludina it is 

 always sharp, and not reflected ; from the pupa by the 

 regularity of the aperture, which is never angular. 



C, planorbula, volvulus, carinata, sulcata, unicarinata, 

 tricarinata, obsoleta, rugosa, labeo, interrupta, ambigua, sem- 

 ilabris, flavula, fasciata, mumia, quaternata, ferruginea, de- 

 cussata, lineolata, mammillaris, ligata, lincinella, orbella, 

 fimbriata, multilabris, elegans, patulum, truncatulum 

 lapidaria, marginata, dentata. 



