bivalve vs quahog

bivalve

noun
  • Any mollusc belonging to the taxonomic class Bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster. 

  • A pericarp in which the seed case opens or splits into two parts or valves. 

quahog

noun
  • A similar edible clam found along coasts around the North Atlantic, generally in deeper waters, the ocean quahog, black quahog, mahogany clam or Icelandic cyprine, Arctica islandica 

  • The largest size of such an edible clam, generally considered only fit for use in chowders and other clam dishes. 

  • An edible clam with a hard shell found along the Atlantic Coast of North America, from species Mercenaria mercenaria, formerly Venus mercenaria. 

verb
  • To dig for quahogs. 

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