puce vs purple dye murex

puce

noun
  • A brownish-purple color, sometimes more or less deep red or grayish. 

adj
  • Of a brownish-purple color, sometimes more or less deep red or grayish. 

purple dye murex

noun
  • A species of medium-sized predatory sea snail, Haustellum brandaris, which secrets a substance that can be used to make a long-lasting purple dye- Tyrian purple. 

How often have the words puce and purple dye murex occurred in a corpus of books? (source: Google Ngram Viewer )