Broomfog's Anima Unnaturale is a compendium of all the weird and strange animals known to the Disc. In Small Gods, it is one of the scrolls "rescued" by Brutha just before the destruction by fire of the Great Library of Ephebe. Brutha just memorises the layout of pictures and strange squiggles on the page, for copying out later when he has a few spare moments.
It hath thee legges of a mermade, the hair of a tortoyse, thee teethe of a fowle, and the wings of a snake. Of course I have only my worde for it, thee beast having the breathe of a furnace and the temperament of a rubber balloon in a hurricane.