sailfish vs swallowtail

sailfish

noun
  • The quillback (Carpiodes cyprinus). 

  • The basking shark (Cetorhinus maximus). 

  • A fish of the genus Istiophorus, having a characteristic sail-like fin on its back. 

swallowtail

noun
  • Any of various butterflies of the family Papilionidae, many of which have a long extension to each hindwing. 

  • A type of tailcoat with two long tapering tails.ᵂᵖ 

  • The forked tail of a swallow. 

  • Anything, such as a burgee, of a similar forked shape. 

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