The hydra, 1608.

ENGLAND - JULY 15: Woodcut of the mythological seven-headed Hydra killed by Hercules. Illustration from �The historie of serpents� by Edward Topsell (1572-1625?) published in London in 1687. Topsell's main source was �Historiae animalium� by Conrad Gesner (1516-1565) published in 1551. He translated and edited Gesner's text, adding long additional sections. The engravings are exact reproductions of those in Gesner's work. This book complemented Topsell's �Historie of foure-footed beastes�, published the year before. It summarized all real and mythical zoological knowledge collected since antiquity, but it was soon rendered obsolete by new discoveries. (Photo by SSPL/Getty Images)