The description of thermalis given by Dupuy is based on comparisons with fluviatilis. The name, introduced by N. Boubée, is considered by Dupuy as a synonym of prevostiana. « Shell similar to the previous one [fluviatilis], but a bit more extended transversely, and of a uniform blueish-black colour, without the lines that one can always see in the previous species. » – D. Dupuy: Histoire naturelle des mollusques terrestres et d’eau douce qui vivent en France, paris 1847-1852, p.594. Dupuy reports that the animal of thermalis is black and not whitish or yellowish as fluviatilis.

« This species seems restricted to this one locality. I have not been able to meet it again in any thermal springs of the Pyrenees, not even in the many other founts of Bagnères. Hot water seems essential to this Neritine; it swarms in the pond where the thermal water is born; it abounds still in the creek which results from it as long as the water retains the heat there; but as new spring waters flow into the brook, the Neritine becomes more rare, and soon there are only a few individuals lost or driven by the current. » – N. Boubée: Bulletin d’histoire naturelle de France sect.3, Paris 1833, p.12.