On 1 March 1508 Vincenzo Berruerio opened his printing shop in the small Piedmontese town of Mondovi with the publication of the Libellus de natura animalium, a moralized bestiary which represents an uncommon vestige of the medieval thought-world in early Renaissance popular culture. The book was in small format and illustrated with about fifty woodcuts of zoological subjects; Berruerio, barely a day after work on the Latin edition was completed, followed it through the press with a vernacular version of the work, Libro del la natura deli animali. The Latin edition, even though only a few copies survive, is well known to bibliographies and book historians, while, on the contrary, copies of the vernacular version seem to have disappeared more rapidly with only a single copy surviving to the present day. Even this unicum was thought to be lost after the antiquarian bookseller Leo Samuel Olschki sold it in 1924 to an unknown client, though Olschki had provided a brief but informative description in the regular feature Livres inconnus des bibliographes in number XXVI of La Bibliofilia. Over time many unsuccessful attempts have been made to find this Mondovi first edition of the vernacular version in a private or public collection. However, a copy of the edition - not perhaps the one sold by Olschki - has been held since 1983 at the Transylvania University Library in Kentucky, USA, which acquired it as part of the large and generous bequest of Miss Clara Sargent Peck. Despite the fact that the book had been catalogued in the library's local online catalogue, its existence remained unknown in Italy. The present article reconstructs the history of the volume and provides a detailed bibliographical description of it, while also examining the context of its publication, in the hope of filling in a significant gap in our knowledge of sixteenth-century printing in Mondovi.