Source : Webster's Revised Unabridged Dictionary (1913)

Galley-worm \Gal"ley-worm`\, n. [Prob. so called because the
   numerous legs along the sides move rhythmically like the oars
   of a galley.] (Zo["o]l.)
   A chilognath myriapod of the genus {Iulus}, and allied
   genera, having numerous short legs along the sides; a
   milliped or ``thousand legs.'' See {Chilognatha}.