Aberdeen Bestiary:
In Asia animal nascitur quod bonnacon dicunt. Cui taurinum capud, ac deinceps corpus omne tantum iuba equina. Cornua autem ita multiplici flexu in se recurrentia, ut si quis in eo offendat non vulneretur, sed quicquid presidii monstro illi frons negat, alvus sufficit. Nam cum in fugam vertit proluvie citi ventris fumum egerit per longitudinem trium iugerum, cuius ardor quicquid attigerit adurit. Ita egerie noxia submovet insequentes.English translation:
In Asia an animal is found which men call bonnacon. It has the head of a bull, and thereafter its whole body is of the size of a bull's with the maned neck of a horse. Its horns are convoluted, curling back on themselves in such a way that if anyone comes up against it, he is not harmed. But the protection which its forehead denies this monster is furnished by its bowels. For when it turns to flee, it discharges fumes from the excrement of its belly over a distance of three acres, the heat of which sets fire to anything it touches. In this way, it drives off its pursuers with its harmful excrement.