In three short papers on the Mollusca of the island of Texel we recorded ten species new to this fauna, namely: Arion subfuscus, A. intermedius, A. hortensis, Planorbis corneus, Cochlodina laminata, Deroceras laeve, Planorbis vortex, Oxychilus draparnaudi and Bithynia tentaculata. It is highly probable that at least the first six of these were introduced by human agency within the last thirty years. In 1966 we found Rissoa membranacea again in an inland water, „de Bol”, on the island of Texel. This species has become extremely rare in our country since the almost total disappearance of eel-grass (Zostera marina) in 1932. „De Bol” is the only locality where Rissoa membranacea was known to occur in the Netherlands in 1966.