flying dragon vs serpent

flying dragon

noun
  • Any lizard in the genus Draco. 

  • Draco volans, a gliding lizard endemic to Southeast Asia. 

  • Used other than figuratively or idiomatically: see flying, dragon. 

serpent

noun
  • A snake, especially a large or dangerous one. 

  • An obsolete wind instrument in the brass family, whose shape is suggestive of a snake (Wikipedia article). 

  • A kind of firework with a serpentine motion. 

  • A subtle, treacherous, malicious person. 

How often have the words flying dragon and serpent occurred in a corpus of books? (source: Google Ngram Viewer )