Tracking the Mysterious Loz in the Secrets of Natural History

The loz is a bovid that in medieval folklore was believed to live in Bohemia. It defended itself against hunters by spraying them with boiling and corrosive water stored in a dewlap beneath its neck. First appearing in the learned tradition with Bartholomaeus Anglicus’ De proprietatibus rerum, it then shows up in a richly illustrated geographical and wonders treatise, the Secrets of Natural History (SNH) of about 1380. This work is a Middle French translation of a small portion (on wonders of various regions of the world) of Pierre Bersuire’s exempla collection Reductorium Morale. The only visual representations of the loz are to be found in the SNH. I argue that both in its written and in its visual existence, the loz is the offspring of two different animals, also more or less imaginary, the bonnacon of the Bestiary and the other, the onager, or wild ass, though a very unusual form of that animal.