zygocardiachttp://www.oed.com/dictionary/zygocardiac_adj%3Ftab%3Dmeaning_and_usezygocardiac, adj.
First published 1921; not fully revised

zygocardiacadjective

  1. 1877–
    Denoting an ossicle in the stomach of the crayfish and other crustaceans (see quot., and cf. pterocardiac n.).
    1. 1877
      A large, elongated postero-lateral or zygocardiac ossicle.
      T. H. Huxley, Manual of Anatomy of Invertebrated Animals vi. 319

Originally published as part of the entry for zygo-, comb. form

zygo-, comb. form was first published in 1921; not fully revised.