EXHIBIT 3.15

                          CERTIFICATE OF INCORPORATION
                                       OF
                             THALIA INTERESTS, INC.

                                    ARTICLE I

                  The name of the corporation is THALIA INTERESTS, INC.

                                   ARTICLE II

                  The registered agent of the corporation is The Corporation
Trust Company. The address of such registered office in the State of Delaware is
The Corporation Trust Center, 1209 Orange Street in the City of Wilmington,
County of New Castle, Delaware 19801.

                                   ARTICLE III

                  The nature of the business or purposes to be conducted or
promoted by the corporation is to engage in any lawful act or activity for which
corporations may be organized under the General Corporation Law of the State of
Delaware.

                                   ARTICLE IV

                  The total number of shares of stock which the corporation
shall have authority to issue is one thousand (1,000) shares of common stock at
a par value of One and No/100 Dollars ($1.00) each.

                                    ARTICLE V

                  The name and mailing address of the incorporator are as
follows:

                           Bob Casey, Jr.
                           2900 South Tower
                           Pennzoil Place
                           Houston, Texas 77002-2781

                                   ARTICLE VI

                  The name and mailing address of the person who is to serve as
the director of the corporation until the first annual meeting of the
stockholders of the corporation or until a successor is elected and qualified is
as follows:

                           Bob Casey, Jr.
                           2900 South Tower
                           Pennzoil Place
                           Houston, Texas 77002-2781



                                   ARTICLE VII

                  In furtherance and not in limitation of the powers conferred
by statute, the board of directors is expressly authorized to adopt, amend or
repeal the bylaws of the corporation.

                                  ARTICLE VIII

                  Elections of directors need not be by written ballot unless
the bylaws of the corporation shall so provide.

                  All action required to be taken or which may be taken at any
annual or special meeting of stockholders of the corporation may be taken
without a meeting, and the power of stockholders to consent in writing, without
a meeting, to the taking of any action is specifically granted.

                  Meetings of stockholders may be held within or without the
State of Delaware, as the bylaws may provide. The books of the corporation may
be kept (subject to any provision contained in the statutes of the State of
Delaware) outside the State of Delaware at such place or places as may be
designated from time to time by the board of directors or in the bylaws of the
corporation.

                                   ARTICLE IX

                  A director of this corporation shall not be liable to the
corporation or its stockholders for monetary damages for breach of fiduciary
duty as a director, except to the extent such exemption from liability or
limitation thereof is not permitted under the Delaware General Corporation Law
as the same exists or may hereafter be amended. Any repeal or modification of
the foregoing sentence shall not adversely affect any right or protection of a
director of the corporation existing hereunder with respect to any act or
omission occurring prior to such repeal or modification.

                                    ARTICLE X

                  The corporation reserves the right to amend, alter or repeal
any provision contained in this Certificate of Incorporation, in the manner now
or hereafter prescribed by the laws of the State of Delaware, and to add
additional provisions authorized by such laws as are then in force. All rights
conferred on the directors or stockholders of the corporation herein or in any
amendment hereof are granted subject to this reservation.

                                   ARTICLE XI

                  The corporation shall indemnify its directors and officers,
and may indemnify its employees and agents, to the extent permitted by the
General Corporation Law of the State of Delaware.

                  I, THE UNDERSIGNED, being the incorporator hereinabove named,
for the purpose of forming a corporation pursuant to the General Corporation Law
of the State of Delaware, do make this Certificate, hereby declaring and
certifying that this is my act and deed

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and the facts herein stated are true, and accordingly have hereunto set my hand
this 29th day of May, 1992.

                                                   /s/ Bob Casey, Jr.
                                                   -----------------------------
                                                       Bob Casey, Jr.

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