237 



very thin, semi-transparent, and papyraceous, with in- 

 ternal and external, slight, transverse ribs, interrupted 

 by the sutures formed at the previous stages of the 

 growth of the opening ; a very wide umbilicus in many 

 species ; and the aperture closed by an ovate, pear- 

 shaped, horny operculum. 



Pyrula canaliculata 



Pyrula ternatana 



carica 



bezoar 



perversa 



rapa 



...... candelabrum 



papyracea 



tuba 



galeodes 



bucephala 



angulafa 



vespertilio 



squamosa 



melongena 



nodosa 



reticulata 



citrina 



ficus 



abbreviata 



ficoides 



neritoidea 



...... spirata 



deformis 



spirillus 



• « lineata 



elongata 



plicata 



[The fossil species are referred to in the Ann. du Mus. 

 vol 2, p. 389-] 



