10 
Pfeifjer, L., Symbolae ad histoi'iam Heliceorum. Sect. III. 1846. 
— Monographia Heliceorum viventium. Vol. I. et II. 1848. Vol. 111. Supplementum, 1853. 
— Monographia Pneumonopomorum viventium. 1852. 
— Genus Helix, Cyclostoma in: Martini und Ghemnitz systematisches Conchylien-Cabinet. 
Edit. 11. 
Potiez et Michaud, Galcrie des Mollusques, ou Gatalogue metbodique descriptiv et raisonne des Mollus- 
ques et coquilles du Museum de Douai. Vol. I. 1838. Vol. II. 1844. 
/teeve, L., Conchologia iconica. Genus Helix, Bulimus, .\chatina. 
Sorverby, G. B., Descriptions, accompained by figures of .several Helices, discovered by F. G. Bowdich 
Esq. at Porto Santo, in: Zoological Journal 1. March 1824. 
IVebb et Berthelot, Synopsis Molluscorum terrestrium et fluviatilium, quos itinei'e per Insulas Ganarien- 
ses observarunt, in: .\nnales des Sciences naturelles, vol. 28. 1833. 
/Food, J., Index testaceologicus. Supplem. 1828. 
