ophidian vs serpentiform

ophidian

adj

  • Of or pertaining to the suborder Serpentes; of, related to, or characteristic of a snake or serpent. 

noun

  • Any species of the suborder Serpentes; a snake or serpent. 

serpentiform

adj

  • Having the form of a serpent. 

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