Een Amerikaanse posthoren in een Purmerendse gracht

On 8 and 15 September 2010, respectively, one empty shell and two living snails of the Ramshorn snail Planorbella duryi (Wetherby, 1879) were collected in a canal in Purmerend, North-Holland, the Netherlands. This species has its origin in the south-eastern part of the United States (Florida). However, since some considerable time it has become a cosmopolitan aquarium snail, and a typical species of botanical gardens. Most probably this exotic species had been dumped in the canal by an aquarium keeper living in the vicinity, who tried to get rid in this way of his excess specimens.