It is for me a pleasure to contribute the following descriptions of chosen rarities to the Jubilary Volume in honour of the highly esteemed Prof. Dr. L. F. DE BEAUFORT and Prof. Dr. J. E. W. IHLE, of the University of Amsterdam. I wish to express my gratitude to Dr. J. WILCKE, Wageningen, and to Mr. W. F. BREURKEN, Amsterdam, for the execution of the drawings.