IX. The Practice of Painting: 585.
585.
HOW YOU SHOULD MAKE AN IMAGINARY ANIMAL LOOK NATURAL.
!mOf representing imaginary animals. You know that you cannot invent animals without limbs, each of which, in itself, must resemble those of some other animal. Hence if you wish to make an animal, imagined by you, appear natural--let us say a Dragon, take for its head that of a mastiff or hound, with
the eyes of a cat, the ears of a porcupine, the nose of a greyhound, the brow of a lion, the
temples of an old cock, the neck of a water tortoise.