De Zandslak Theba pisana (O.F. Müller, 1774): een nieuwe soort voor Purmerend

In the autumn of 2016 I discovered a colony of the Sand hill snail Theba pisana at a new roundabout in Purmerend, province of North Holland, the Netherlands. The site is quite distant from known habitats of the Sand hill snail in the Netherlands. The snails most probably reached the site with building sand brought from somewhere along the coast and used to construct the roundabout.