Over de indeeling der vormen van het geslacht Cepaea

Since the variability of molluscs is studied more and more in the Netherlands by various members of the Malacological Society, it has become necessary for those persons who studied the variability of our common Cepaea, to know the names they had to give to their specimens. Asked to give information I tried to find out a system, for central Europe and especially for our own country, a system with the elimination of rare or scarce forms, scarcely to expect with us and a system that at the same time was rather simple and acceptable for our members. In the admirable monograph of Taylor we find much information and I studied this fine book thoroughly. Taylor’s book gives so much forms and these forms are classified on such various ways that it was impossible to give a copy of all the varieties in Taylor’s book in a paper for our readers. Moreover these forms were not given in a taxonomical way. After long considerations, partly also based upon taxonomical principles in botany, I resolved to divide the Cepaea nemoralis nemoralis as generally found in central Europa and in the Netherlands into two so called greges (from latin grex). Pointing out the importance of the fascialba character as a phylogenetic one, I named the two greges: vulgaris and fascialba. Accepting further the average diameter of the shell as important for a division, I noted in each grex three subspecies, already accepted in the literature as minor, media and major. Only the subsp. media is found with us. It contains the seven varieties of colour of the lip and peristome as given by Taylor. Each variety has a great many subvarieties based upon the various colours of the shell, the names given to these subvarieties are to follow by the band formula’s as sufficiently known from our manuals. There is further place to take up still minor variation as forma or subforma e.g. forma lateritia or forma hyalozonata or forma pellucida etc. Strictly applying the rules it is not allowed to take up the same name for more than one minor group, but as it is found impossible to invent new names without a total knowledge of all the enormous quantity of forms hitherto described, we are forced to accept this contradiction.