ne plus ultra vs spider's ankles

ne plus ultra

noun
  • The perfect or most extreme example of its kind; the ultimate. 

  • A prohibition against proceeding further; an insuperable obstacle or limiting condition. 

  • The highest, ultimate point of achievement which can be reached; perfection. 

spider's ankles

noun
  • Something that is regarded as outstanding. 

How often have the words ne plus ultra and spider's ankles occurred in a corpus of books? (source: Google Ngram Viewer )