Carychium tridentatum

Carychium tridentatum is a species of minute air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Ellobiidae.

Description
The shell is 1.8-2.3 mm high x 0.8-0.9mm. wide. The shell is more slender than that of Carychium minimum. If the last whorl above the aperture is opened this shows the parietalis (a spiral ridge on the parietal region projecting into the interior of the shell) descending in a characteristic double curve (see figure below).

Distribution
This species occurs in European countries and islands the Mediterranean, the Caucasus region and North Africa. It is recorded from Siberia as Carychium striolatum J.R. Bourguignat, 1857 (synonym)

The European countries include: Albania, Andorra, Austria, Azores, Belarus, Bulgaria, Channel Islands , Croatia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Italy, Kaliningrad, Latvia, Liechtenstein, Lithuania, Luxembourg, Madeira, Moldova, Montenegro, Norway, Romania, Serbia, Slovenia, Spain, Sweden, Switzerland.
 * Belgium
 * Bulgaria
 * Czech Republic
 * Netherlands
 * Poland
 * Slovakia
 * Great Britain
 * Ireland
 * Ukraine

It has been introduced to North America, including to:
 * British Columbia, Canada