Marine Gastrotricha and Kinorhyncha from Scheveningen

In the first three months of 1937 some Gastrotricha and Kinorhyncha were collected by the author at the beach of Scheveningen. Up to the present no members of these classes were recorded from this part of the North Sea, and moreover, they are all new for the fauna of the Netherlands. Therefore I summarized the results of the examination in the present paper. During neap tide some sand of the beach was put into glassjars, which were beforehand partially filled with sea water. The sand was taken from the surface of the beach, as near to the water line as possible. As described by Remane (1936, pp. 234—235) the glassjars were put in a quiet spot without aeration for 1—2 weeks. After this time every day a proof was taken with a pipette from the surface of the sand, and examined microscopically in Petri-dishes. The collected specimens are inhabitants from the part of the beach that is wetted and dried up twice a day. Therefore the occurrence of these species is "medio-littoral" (Zaneveld, 1937, p. 477). This only incidentally studied habitat is characterized by extraordinary varying conditions, because the structure of the bottom and especially the size of the sand grains is dependent on the mechanical effect of the water movement, on the wind, and on the sunshine. On account of this we can expect a large number of species, recorded from different habitats. The Gastrotricha dealt with here occur in the following biotopics (Remane, 1936, p. 214). Shell formation: Macrodasys cephalatus and Dactylopodalia typhle. Coarse gravel: Dactylopodalia typhle, Platydasys maximus and Aspidiophorus marinus.