Source : Webster's Revised Unabridged Dictionary (1913)

--Udall.

   {Pill beetle} (Zo["o]l.), any small beetle of the genus
      {Byrrhus}, having a rounded body, with the head concealed
      beneath the thorax.

   {Pill bug} (Zo["o]l.), any terrestrial isopod of the genus
      {Armadillo}, having the habit of rolling itself into a
      ball when disturbed. Called also {pill wood louse}.