Zirfaea crispata (Linné 1758), var. truncata nov. var

In November 1936 the author found some specimens of Zirfaea crispata (L.) washed ashore on the beach of the isle of Texel, which showed a remarkable difference with the typical form of this species. As this form of Z. crispata was not found in litterature the author describes it in the present article as the variety truncata nov., chiefly characterised by the following points: The posterior side is very high and much truncated. The shells are thicker than specimens of the forma typica whereas the groove running from the umbo to the ventral margin is well marked on the inner side. The sculpture on the anterior side of the outer surface is coarse and distinctly marked.