APPOINTMENT OF ATTORNEY-IN-FACT

         I hereby authorize the filing with the Securities and Exchange
Commission of any and all reports on Forms 3, 4 and 5 ("Reports"), or any
substitute form hereafter adopted by the Securities and Exchange Commission, as
may from time to time be required under Section 16(a) of the Securities Exchange
Act of 1934, as amended. I hereby appoint Messrs. Clark Hinckley, Doyle L.
Arnold and Thomas E. Laursen, and each of them, as my attorneys-in-fact with
power to any of them to sign any and all Reports and any and all amendments to
Reports or documents required to complete the filing of Reports or amendments
thereto with the Securities and Exchange Commission on my behalf.


                         Dated the 2 of December, 2005.



                                                    /s/ Paul B. Murphy
                                                    --------------------


STATE OF TEXAS      )
                    )   ss.
COUNTY OF HARRIS    )


                                 ACKNOWLEDGMENT

     On this 2 day of December, 2005,  personally  appeared  before me Paul R.
Murphy, known to me to be the  person  whose  name is  subscribed  to the
above instrument  and who  acknowledged  that (s)he executed the same for the
purposes therein contained.

         IN WITNESS WHEREOF, I have hereunto set my hand and official seal.

                                                    /s/ Karen E. Dillard
                                                    ----------------------
                                                             NOTARY PUBLIC


My Commission Expires:                                        Residing At:

KAREN E. DILLARD
NOTARY PUBLIC
STATE OF TEXAS
My Commission Expires
November 05, 2007