"And Leonardo was always interested in monsters. He shut himself away and studied all kinds of unpleasant little things - lizards, spiders, bats - and borrowed from all, blending and flavoring them with his own genius."
"If Leonardo da Vinci, a curly-blond boy in his teens, had studied lizards, bats and spiders for this, he had not hodge-podged his studies. Anyone else would have been content with a lizard's body, a spider's knuckly jointed legs, a bat's wings. Not so Leonardo, master of his eye and hand and brush even before his voice had changed and the first peachy fuzz had sprouted for the the beginning of that apostolic beard he was to wear."
"The legs - there seemed to be a great many of them - were hairy and jointed, but those in front, at least, bore hand-like extremities, reminiscent of the forefeet of lizards. Those wings were true da Vinci work; Norbier remembered the tales of how da Vinci, seeking to invent the airplane centuries before Langley or Wright, studied painstakingly ever flying creature, bat, bird and insect. As for the thing's head, that was apparently meant to seem a squat, dark-furred blotch, with two glowing close-set eyes peering from the thick fur as from an ambush. A real face to it, flattened like a bat's and a mouth with a jaw of ophidian shallowness, but a little open to show... yes, fangs. No wonder that everyone who saw the thing, from Piero da Vinci to the present, squared his shoulders a trifle to dissemble a shiver."
"It seemed to crouch there, then to hoist itself erect on the tips of its multiple claws. Among the curved, jointed brackets of its hind legs hung a puffy body, like a great crammed satchel. The integument had pattern, like scales, and from the spaces between the scales sprouted tufts and fringes of dark fur, like plush grown wild. And it had wings, also scaly and tufted, ribbed like a bat's that winnowed and stirred above its bulk. The head, a shaggy ball, craned in his direction. Deep within the thicket of fur upon the face clung two wise, close-set eyes, that glowed greenly, then redly, at him. Between and above them the fur seemed to part in two directions, as if the undeveloped forehead frowned. A mouth opened, the light caught a stockade of white, irregular, pointed fangs. A great gout of foam came out, and fell splashing on the floor."
"The two foremost limbs rose, and at the ends Norbier saw hand-like claws, like the front feet of a big, big lizard."
Manly Wade Wellman, The Leonardo Rondache