Section 63. Service of answer on state or public corporation

In an action
  to foreclose a lien for a public improvement each defendant named in the
  original summons shall within  forty  days  after  the  service  of  the
  complaint  on  him serve upon the state or public corporation, a copy of
  his answer When the city of New York is a party such  service  shall  be
  made on the corporation counsel.