The Mollusca of the estuarine region of the rivers Rhine, Meuse and Scheldt in relation to the hydrography of the area. III. The genus Pisidium

The ecology and distribution of 13 species of Pisidium in the estuarine area of the rivers Rhine, Meuse and Scheldt have been investigated. These are P. amnicum, P. moitessierianum, P. supinum, P. henslowanum, P. casertanum. P. personatum, P. obtusale, P. nitidum, P. milium, P. hibernicum, F. subtruncatum, P. pulchellum, and P. pseudosphaerium. From the data obtained it is concluded that four species will colonize the future fresh Delta lakes in an early stage: P. casertanum, P. henslowanum, P. nitidum, and P. subtruncatum. Later this group will probably be followed by P. personatum, P. obtusale, and P. milium.