Source : Webster's Revised Unabridged Dictionary (1913)

Dynastidan \Dy*nas"ti*dan\, n. [Gr. ?, fem. of ?. See {Dynast}.
   The name alludes to the immense size of some species.]
   (Zo["o]l.)
   One of a group of gigantic, horned beetles, including
   {Dynastus Neptunus}, and the Hercules beetle ({D. Hercules})
   of tropical America, which grow to be six inches in length.