SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G


                   Under the Securities Exchange Act of 1934





                         QUICKTURN DESIGN SYSTEMS INC.
                                (Name of Issuer)



                                  COMMON STOCK
                         (Title of Class of Securities)



                                   74838E102
                                 (CUSIP Number)



      Check the following box if a fee is being paid with this statement.   /X/
(A fee is not required only if the filing person:  (1) has a previous  statement
on file  reporting  beneficial  ownership of more than five percent of the class
of  securities  described in Item 1; and (2) has filed no  amendment  subsequent
there to reporting beneficial ownership of five percent or less of such class.)
(See Rule 13d-7.)







CUSIP No. 74838E102                   13G                    Page 1 of 3 Pages
          ---------                                              ---  ---



1) NAME OF REPORTING PERSON
   S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                                            J. & W. SELIGMAN & CO. INCORPORATED
                                                                     13-3043476

2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                        (a) /x/

                                                                        (b) /_/

3) SEC USE ONLY



4) CITIZENSHIP OR PLACE OF ORGANIZATION

                                                                       DELAWARE


 NUMBER OF SHARES     (5) SOLE VOTING POWER                  710,400
BENEFICIALLY OWNED    (6) SHARED VOTING POWER                 47,600
BY EACH REPORTING     (7) SOLE DISPOSITIVE POWER             758,000
 PERSON WITH          (8) SHARES DISPOSITIVE POWER               -0-

9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

                                                                        758,000

10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES



11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

                                                                          5.85%

12) TYPE OF REPORTING PERSON

                                                                             IA








CUSIP No. 74838E102                    13G                    Page 2 of 3 Pages
          ---------                                               ---  ---

Item 1(a) Name of Issuer:

          QUICKTURN DESIGN SYSTEMS INC.

Item 1(b) Address of Issuer's Principal Executive Offices:

          440 CLYDE AVENUE
          MOUNTAIN VIEW, CALIFORNIA  94043

Item 2(a) Name of Person Filing:

          J. & W. SELIGMAN & CO. INCORPORATED

Item 2(b) Address or Principal Business Office or, if none, Residence:

          100 PARK AVENUE
          NEW YORK, NEW YORK  10017

Item 2(c) Citizenship:

          DELAWARE CORPORATION

Item 2(d) Title of Class of Securities:

          COMMON STOCK

Item 2(e) CUSIP Number:

          74838E102

Item 3    If this statement is filed pursuant to Rules 13-d, or 13-2(b), check
          whether the person is filing as a:  Investment Adviser registered
          under Section 203 of the Investment Advisers Act of 1940
                                                                            /X/
Item 4(a) Amount Beneficially Owned:

          758,000

Item 4(b) Percent of Class:

          5.85%

Item 4(c) Number of shares as to which such person has:

     (i)      sole power to vote or to direct the vote                  710,400
     (ii)     shares power to vote or direct the vote                    47,600
     (iii)    sole power to dispose or to direct the disposition of     758,000
     (iv)     shares power to dispose or to direct the disposition of       -0-






CUSIP No. 74838E102                    13G                    Page 3 of 3 Pages
          ---------                                               ---  ---

Item 5    Ownership of Five Percent or Less of a Class:

          NOT APPLICABLE

Item 6    Ownership of More than Five Percent on Behalf of Another Person:

          NOT APPLICABLE

Item 7    Identification and Classification of the Subsidiary which acquired
          the security being reported on by the Parent Holding Company:

          NOT APPLICABLE

Item 8    Identification and Classification of Members of the Group:

          NOT APPLICABLE

Item 9    Notice of Dissolution of Group:

          NOT APPLICABLE

Item 10   Certification

          By signing below I certify that, to the best of my
          knowledge and belief, the securities referred to above
          were acquired in the ordinary course of business and
          were not acquired for the purpose of and do not have
          the effect of changing or influencing the control of
          the issuer of such securities and were not acquired in
          connection with or as a participant in any transaction
          having such purpose or effect.

          Signature

          After reasonable inquiry and to the best of my knowledge and belief,
          I certify that the information set forth in this statement is true,
          and correct.



          Lawrence P. Vogel
          Senior Vice President, Finance


          FEBRUARY 9, 1995
          Date