derg vs flying dragon

derg

noun

  • Dragon. 

flying dragon

noun

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

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

  • Any lizard in the genus Draco. 

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