Source : Webster's Revised Unabridged Dictionary (1913)

Hydrocorallia \Hy`dro*co*ral"li*a\, n. pl. [NL. See {Hydra}, and
   {Coral}.] (Zo["o]l.)
   A division of Hydroidea, including those genera that secrete
   a stony coral, as Millepora and Stylaster. Two forms of
   zooids in life project from small pores in the coral and
   resemble those of other hydroids. See {Millepora}.