cognomen vs family name

cognomen

noun
  • A nickname or epithet by which someone is identified. 

  • The third part of the name of a citizen of Ancient Rome. 

  • Surname. 

family name

noun
  • A given name common in a family, or already borne by someone in the family (in the context of naming someone in the family after that family member). 

  • A surname. 

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