sept vs stirps

sept

noun
  • A clan, tribe, or family, proceeding from a common progenitor; especially, one of the ancient clans of Ireland. 

  • An enclosure; a railing. 

stirps

noun
  • A progenitor of a branch of a family. 

  • A branch of a family. 

  • A superfamily of animals or plants. 

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