\Li*thod"o*mus\, n. [NL. See {Lithodome}.] (Zo["o]l.)
A genus of elongated bivalve shells, allied to the mussels,
and remarkable for their ability to bore holes for shelter,
in solid limestone, shells, etc. Called also {Lithophagus}.
Note: These holes are at first very small and shallow, but
      are enlarged with the growth of the shell, sometimes
      becoming two or three inches deep and nearly an inch
      diameter.