In aquatic Pulmonata the osphradium is retained.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5" by Various
The Family Succinea really ranks with the land shells, as belonging to the sub-order Pulmonata or lung-breathing molluscs.
"Our British Snails" by John William Horsley
These fresh-water and land-molluscs which possess a lung-sac instead of gills constitute the order Pulmonata.
"Elementary Zoology, Second Edition" by Vernon L. Kellogg