'Trigonia' definitions:

Definition of 'Trigonia'

From: GCIDE
  • Trigonia \Tri*go"ni*a\, n. [NL. See Trigon. So called in allusion to the triangular shape of some species.] (Zool.) A genus of pearly bivalve shells, numerous extinct species of which are characteristic of the Mesozoic rocks. A few living species exist on the coast of Australia. [1913 Webster]