Trigonia

1 definition found

From The Collaborative International Dictionary of English v.0.48 [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]