In the library of the Royal Zoological Society »Natura Artis Magistra” at Amsterdam, there is a copy of the descriptive catalogue of the collection of birds etc. made by Mr. A. Vroeg and sold at the Hague in the year 1764. This is one of the rarest prints, besides this only one copy, preserved in the library of the Linnean Society of London, is known. The attention of Zoologists to this Catalogue has been drawn by Mr. C. D. Sherborn, when writing his Index Animalium, and the new names in the catalogue were attributed by Mr. Sherborn in his Index to A. Vroeg; but afterwards he was informed by Dr. C. W. Richmond, that P. S. Pallas was the author of the new names in the »adumbratiunculae” at the end of the catalogue (cf. Smithsonian Misc. Coll. XLVII, 1905, p. 332). I had the opportunity, by kind permission of Dr. C. Kerbert, Director of the Zoological Society of Amsterdam, to examine the copy in possession of that Society, for which I tender my sincere thanks to that gentleman.