Wulken, een aanvulling

In a previous paper on distinct varieties of the Whelk three ‘formas’ were identified that, according to Mr. Koen Fraussen of the Belgian Society for Conchyliology, should all be designated ‘forma vulgare da Costa, 1778’. Among these was a Whelk shell labelled by the author as ‘forma littoralis’. Mr. Fraussen sent me two specimens of that variety which are shown with this addendum.