Lamellibranchiata autochthoon nieuw voor de Nederlandse fauna

During the last five years the fauna of the sea dikes along the Dutch coast has been thoroughly studied. In the course of these investigations five species of Lamellibranchiata have been found which were hitherto not known living in the Netherlands, though they are more or less frequently washed ashore attached to floating objects. Heteranomia squamula (L.) was found on a stone dredged in the harbour of West-Terschelling in August 1949, on the sea dike near Den Helder also in August 1949, and on the sea dike near Haamstede in the island of Schouwen in August 1950. All the specimens were found living in the sublittoral zone. Kellia suborbicularis (Mont.) appears to live in small numbers in the sublittoral zone of the sea dike near Den Helder and Huisduinen. Lasaea rubra (Mont.) was found once, attached to the under side of a stone in the sublittoral zone of the sea dike of Den Helder. Two specimens of Sphenia binghami Turton were collected among hydroids near Huisduinen in July 1948, and three young ones of the same species at low water level at the eastern end of the sea dike at Den Helder. Three young specimens of Hiatella arctica (L.) were found attached to a stone in the sublittoral zone of the outer side of the sea dike of the Kistersinlaag, just West of Zieriksee in the island of Schouwen.