Perhaps the most remarkable beast in Rauner’s collections is the depiction of Albertus Seba’s specimen of a seven-headed hydra in his collection of natural wonders, Locupletissimi rerum naturalium (Amsterdam, 1734-65). He admits in the text to being doubtful at first, but becoming convinced that the specimen was true to nature. To a European collector reared on the classics, a seven-headed hydra brought back by sailors traveling into new worlds would probably have been less questionable than a duck-billed platypus.
Seba was one of the great collectors of all time. His first natural history collection was sold to the czar of Russia and became the seed collection for the natural history museum in St. Petersburg. With the proceeds of the sale, he assembled his second great collection cataloged here.
To see it in "real" life, ask for Rare Book QH41.S4.