The Collaborative International Dictionary of English v.0.48:

Erythrin \E*ryth"rin\, Erythrine \E*ryth"rine\, n. [Gr.
   'eryqro`s red.]
   1. (Chem.) A colorless crystalline substance, C20H22O10,
      extracted from certain lichens, as the various species of
      Rocella. It is a derivative of orsellinic acid. So
      called because of certain red compounds derived from it.
      Called also erythric acid.
      [1913 Webster]

   2. (Min.) See Erythrite, 2.
      [1913 Webster]