The famous ‘paper museum’ with illustrations of zoological and botanical species collected by Johannes le Francq van Berkhey (1729–1812), with emphasis on the drawings of insects for volume 4 of Albertus Seba’s Locupletissimi rerum naturalium thesauri

Van Berkhey, Reader in Natural History at the University of Leiden in the Dutch Republic, was financially ruined around 1784–85, an event which led to the sale of his books and manuscripts and his natural history cabinet, which were widely dispersed. He had assembled a famous iconographical collection of over 6,000 drawings and prints of naturalia (many of which he had drawn himself), arranged according to the Linnaean system. These were sold by auction in 1785 as an entity, to an unknown bidder, for the cabinet of King Carlos III of Spain and then preserved in Madrid. This fact has become internationally known only recently.
In his auction catalogue, Van Berkhey emphasised the importance of his extensive collection of original drawings of insects, which were models for the engravings in volume 4 of Albertus Seba’s Thesaurus (published in 1765). About 200 insect drawings were fraudulently removed from the Museo Nacional de Ciencias Naturales (MNCN) in Madrid around 1982, but in 2009 these were restored to the archive of the MNCN.
During the eighteenth century new species were often described, especially by Linnaeus himself, from images in books or drawings, without the addition of illustrations. The Van Berkhey iconographical collection as a whole, still preserved in Madrid, could serve as an important source for solving taxonomic problems since it contains illustrations of new species, so-called iconotypes: if the real type specimen (the holotype) is missing, a good illustration of it can help.