phocine vs true seal

phocine

noun
  • A member of the subfamily Phocinae, comprising the "true" or "earless" seals. 

adj
  • Pertaining to a seal (or similar pinnipeds); seallike. 

true seal

noun
  • Any of the seals in the taxonomic family Phocidae; earless seal. 

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