Over de landslakkenfauna van Oostvoorne

In this paper the landmollusca of the island of Voorne are dealt with. When visiting the island in 1934, collecting was much hampered by the very dry weather; nevertheless the present author could prepare a checklist of 28 species. It was striking that such a common snail in the Netherlands as Gonyodiscus rotundatus (Müll.) could not be detected in the region studied that year. Other equally common species were only represented by small numbers of specimens, with the exception of Theba cantiana (Mont.), which was more abundant in fine living specimens. Assiminea grayana Fleming was found in very large colonies in two widely separated localities. An exact locality of Phytia myosotis (Drap.) could not be detected, although an empty shell was collected along the seacoast. Of the larger genera Arianta and Cepaea only a few specimens were found; large populations of them, so often observed in other localities, appeared to be lacking here. The genus Clausilia appeared to be absent on the island, but Balea was found in two widely separated localities on big elmtrees and on Populus. Trichia hispida (L.) proved to be rather well distributed. All the shells of this species belonged to a rather narrowly umbilicated variety with a relatively high spire. They therefore differ from the typical Trichia hispida, which is more depressed and widely umbilicated.