Over Albinisme bij Gastropoden. II

In his first article the author writes about variability of Gastropods and especially treats the albinism; he indicates the occurrence of albino shells of Planorbis corneus in the Netherlands, hitherto observed on 3 localities near the town of Leiden. They belong to var. albina Moq. Tand., having a pigmented animal and a pure white shell with a white inner peristom. In the second article albinism of the Cepaea-species C. hortensis and C. nemoralis is treated. Different forms of these species are found in the Netherlands, especially the varieties fusca Poir. of C. hortensis and its albino shells and the varieties lurida Moq. Tand. of C. hortensis and the var. hyalozonata Taylor of C. nemoralis. The author emphasizes that here, in contradistinction to Dr. Boettger’s opinion, the variability of both species of Cepaea is caused by hybridization so that each species forms a hybridogeneous population in which the albinistic forms occur too. With exception of some European races, the problem may be reduced to and treated as a genetical one. White-lipped C. nemoralis and dark-lipped C. hortensis are according to the author not to accept as geographical forms.