UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                                 (Rule 13d-101)
  Information to be Included in Statements Filed Pursuant to Rule 13d-1(a) and
               Amendments Thereto Filed Pursuant to Rule 13d-2(a)

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 3)*

                         THE HOUSTON EXPLORATION COMPANY
--------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, par value $ .01 per share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    44212010
--------------------------------------------------------------------------------
                                 (CUSIP Number)

                               John J. Bishar, Jr.
--------------------------------------------------------------------------------
                     Senior Vice President & General Counsel
                               KeySpan Corporation
                              One MetroTech Center
                            Brooklyn, New York 11201
                                 (718) 403-1000
                                 With a copy to:

                              William R. Dougherty
                         Simpson Thacher & Bartlett LLP
                              425 Lexington Avenue
                            New York, New York 10017
                                 (212) 455-2000
--------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                  May 24, 2004
--------------------------------------------------------------------------------
             (Date of Event which Requires Filing of this Statement)

     If the filing  person has  previously  filed a statement on Schedule 13G to
report the  acquisition  that is the subject of this Schedule 13D, and is filing
this schedule  because of sections  240.13d-1(e),  240.13d-1(f) or 240.13d-1(g),
check the following box. |_|

     Note:  Schedules  filed in paper format shall include a signed original and
five copies of the schedule,  including all exhibits.  See section 240.13d-7 for
other parties to whom copies are to be sent.

     *The  remainder  of this cover  page  shall be filled  out for a  reporting
person's  initial  filing on this  form with  respect  to the  subject  class of
securities,  and for any subsequent amendment containing information which would
alter disclosures provided in a prior cover page.

     The  information  required on the remainder of this cover page shall not be
deemed to be "filed"  for the purpose of Section 18 of the  Securities  Exchange
Act of 1934 ("Act") or otherwise  subject to the  liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however,  see
the Notes).




                                                                Page 2 of 12

----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
            KeySpan Corporation
            I.R.S. Identification No. 11-3431358
----------- --------------------------------------------------------------------
    2.      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a)[ ]
                                                              (b)[ ]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY
----------- --------------------------------------------------------------------
    4.      SOURCES OF FUNDS*

            Not Applicable
----------- --------------------------------------------------------------------
    5.      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)[ ]
----------- --------------------------------------------------------------------
    6.      CITIZENSHIP OR PLACE OF ORGANIZATION

            New York
----------------------- ---------- ---------------------------------------------
   NUMBER OF            7.  SOLE VOTING POWER
    SHARES
 BENEFICIALLY                  17,380,392 (indirectly through KeySpan Energy
                                           Corporation and THEC Holdings Corp.)
   OWNED BY             ---------- ---------------------------------------------
    EACH                8.  SHARED VOTING POWER
  REPORTING

   PERSON               ---------- ---------------------------------------------
    WITH                9.  SOLE DISPOSITIVE POWER

                               17,380,392 (indirectly through KeySpan Energy
                                           Corporation and THEC Holdings Corp.)
                        ---------- ---------------------------------------------
                        10. SHARED DISPOSITIVE POWER

----------- --------------------------------------------------------------------
   11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON


            17,380,392 (indirectly through KeySpan Energy Corporation and
                        THEC Holdings Corp.)
----------- --------------------------------------------------------------------
   12.      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES* [ ]
----------- --------------------------------------------------------------------
   13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                                                55%
----------- --------------------------------------------------------------------
   14.      TYPE OF REPORTING PERSON*

                                                HC
----------- --------------------------------------------------------------------




                                                                Page 3 of 12

----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
            KeySpan Energy Corporation
            I.R.S. Identification No. 11-3344628
----------- --------------------------------------------------------------------
    2.      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a)[ ]
                                                              (b)[ ]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY
----------- --------------------------------------------------------------------
    4.      SOURCES OF FUNDS*

            Not Applicable
----------- --------------------------------------------------------------------
    5.      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)[ ]
----------- --------------------------------------------------------------------
    6.      CITIZENSHIP OR PLACE OF ORGANIZATION

            New York
----------------------- ---------- ---------------------------------------------
   NUMBER OF
     SHARES              7.  SOLE VOTING POWER
  BENEFICIALLY

   OWNED BY                      17,380,392 (indirectly through THEC Holdings
                                             Corp.)
     EACH               ---------- ---------------------------------------------

   REPORTING             8.  SHARED VOTING POWER
    PERSON
     WITH               ---------- ---------------------------------------------
                         9.  SOLE DISPOSITIVE POWER

                                  17,380,392 (indirectly through THEC Holdings
                                              Corp.)
                         ---------- --------------------------------------------
                         10. SHARED DISPOSITIVE POWER

----------- --------------------------------------------------------------------
   11.      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            17,380,392 (indirectly through THEC Holdings Corp.)
----------- --------------------------------------------------------------------
   12.      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES* [ ]

----------- --------------------------------------------------------------------
   13.      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                                             55%
----------- --------------------------------------------------------------------
   14.      TYPE OF REPORTING PERSON*

                                             CO
----------- --------------------------------------------------------------------




                                                                Page 4 of 12
----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON
            THEC Holdings Corp.
            I.R.S. Identification No. 76-0489610
----------- --------------------------------------------------------------------
    2.      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a)[ ]
                                                              (b)[ ]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY
----------- --------------------------------------------------------------------
    4.      SOURCES OF FUNDS*

            Not Applicable
----------- --------------------------------------------------------------------
    5.      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)[ ]
----------- --------------------------------------------------------------------
    6.      CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
----------------------- ---------- ---------------------------------------------
   NUMBER OF
    SHARES               7. SOLE VOTING POWER
 BENEFICIALLY

  OWNED BY                            17,380,392
   EACH                 ---------- ---------------------------------------------

  REPORTING              8. SHARED VOTING POWER
   PERSON
    WITH                ---------- ---------------------------------------------
                         9. SOLE DISPOSITIVE POWER

                                      17,380,392
                        ---------- ---------------------------------------------
                        10. SHARED DISPOSITIVE POWER

--------------------------------------------------------------------------------
   11.       AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

             17,380,392
----------- --------------------------------------------------------------------
   12.       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
             SHARES* [ ]

----------- --------------------------------------------------------------------
   13.       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

                                         55%
----------- --------------------------------------------------------------------
   14.       TYPE OF REPORTING PERSON*

                                         CO
----------- --------------------------------------------------------------------




                                                                Page 5 of 12

Item 1.  Security and Issuer

          Item 1 is hereby amended and restated as follows:

     This  Amendment  No. 3 (the  "Amendment")  to Schedule  13D relating to the
Common  Stock,  par value $0.01 per share (the "Common  Stock"),  of The Houston
Exploration  Company, a Delaware  corporation (the "Issuer") is filed by KeySpan
Corporation  (f/k/a  BL  Holding  Corp.),  a New York  corporation  ("KeySpan"),
KeySpan Energy Corporation,  a New York corporation  ("KEC"),  and THEC Holdings
Corp.,  a Delaware  corporation  ("THEC"  and,  together  with  KeySpan and KEC,
"Reporting  Persons"),  to further  amend the Schedule  13D that was  previously
filed on October 8, 1997 and amended by Amendment No. 1 thereto,  filed on April
7, 2000 and Amendment No. 2 thereto,  filed on March 3, 2003.  Unless  otherwise
indicated, all capitalized terms used but not defined in this Amendment have the
same  meaning  as set  forth in the  Schedule  13D as  previously  amended.  The
principal  executive offices of the Issuer are located at 1100 Louisiana,  Suite
2000, Houston, Texas 77002-5219.

Item 2.  Identity and Background

          Item 2 is hereby amended by adding the following text:

          Annexes A-1,  A-2 and A-3 are hereby  amended and restated as attached
          hereto.

Item 4.  Purpose of Transaction

          Item 4 is hereby amended and restated as follows:

     KeySpan,  THEC and Issuer have announced that they plan to enter into to an
agreement  under which THEC will transfer to Issuer up to  10,800,000  shares of
Common  Stock  in  exchange  for  all of the  stock  of a  wholly  owned  Issuer
subsidiary,  Seneca-Upshur  Petroleum,  Inc  ("Seneca").  At  the  time  of  the
exchange,  Seneca  will hold all of  Issuer's  Appalachian  Basin  assets and an
amount of additional  cash  calculated to equalize the value of the Common Stock
being exchanged. KeySpan and Issuer have ascribed a value of $60 million dollars
to  the  Appalachian  Basin  producing  assets.  At  December  31,  2003,  these
properties  had proved  reserves  of 50.5  billion  cubic  feet of  natural  gas
equivalent (Bcfe), or approximately 7% of Issuer's total proved reserves.

     The value that  KeySpan will  receive for its  10,800,000  shares of Common
Stock in the  proposed  exchange  will be  determined  by a formula,  one of the
components  of which is the  ultimate  public  offering  price of the  shares of
Common Stock in the offering.  Assuming a public offering price of $45.01 (which
was the last reported sales price of Common Stock on the New York Stock Exchange
on May 21,  2004),  KeySpan  will  receive a per share value for its  10,800,000
shares of Common Stock that is equal to $40.09.  The value per share received by
KeySpan will increase or decrease,  as the case may be, by  approximately  $0.51
per share for a  corresponding  $1.00 increase or decrease in the assumed public
offering price.

     If the  proposed  exchange  is  consummated,  KeySpan  would own  6,580,392
shares, or approximately  24%, of Issuer's  outstanding Common Stock. The Issuer
may  contribute  a  portion  of  the  net  proceeds  from  any  exercise  by the
underwriters of their over-allotment option prior to the closing of the offering
to Seneca and up to 310,000  additional  shares of Common  Stock may be redeemed
from KeySpan in the proposed exchange (in which case KeySpan would own 6,270,392
shares,  or  approximately  23%,  of  Issuer's  outstanding  Common  Stock).  In
addition, KeySpan would reduce its representation on Issuer's Board of Directors
to two directors  from five and the Chief  Executive  Officer of KeySpan will no
longer serve as Chairman of the Board of Directors of the Issuer.

     In addition, KeySpan plans to enter into an underwriting agreement pursuant
to which it would agree, among other things, not to transfer,  without the prior
written  consent of the  underwriters  and  subject to certain  exceptions,  any
shares of Common  Stock  during the period  ending 90 days after the date of the



                                                                Page 6 of 12

prospectus  supplement  relating to the offering of shares of Common  Stock.  As
part of the proposed transactions, THEC would also agree that, upon consummation
of the proposed transactions,  for a period of three years, THEC would agree not
to increase its ownership interest in the Issuer above the ownership interest it
has at the time of consummation.

     Since consummation of the proposed  transactions is subject to each party's
satisfaction  with the public offering price, no assurance can be given that the
proposed transactions will be completed.

     The preceding  summary of the proposed  transactions  is not intended to be
complete  and is  qualified in its entirety by reference to the full text of the
press release  issued by KeySpan,  a copy of which is filed as Exhibit 8 hereto,
and which is incorporated herein by reference.

     KeySpan,  KEC and THEC intend to review the performance of their investment
in the Issuer from time to time.  Depending on various  factors,  including  the
business,  prospects  and  financial  position  of the  Issuer,  the current and
anticipated  future  price levels of the Common  Stock,  the  conditions  in the
securities markets and general economic and industry conditions,  as well as the
benefits of diversification and the other investment  opportunities available to
them,  KeySpan,  KEC and THEC will  take  such  actions  with  respect  to their
investment in the Issuer as they deem appropriate in light of the  circumstances
existing from time to time.  Subject to the terms of any agreement  entered into
in connection with the proposed transactions, KeySpan, KEC and THEC may purchase
additional  equity in the Issuer or may dispose of some or all of their holdings
in the open market, in public offerings,  in private negotiated  transactions or
in other transactions, including derivative transactions.

     Other than as described above, none of KeySpan,  KEC and THEC has any plans
or proposals  that relate to or would result in any of the actions  described in
subparagraphs (a) through (j) of Item 4 of Schedule 13D (although  KeySpan,  KEC
and THEC reserve the right to develop such plans).

Item 5.  Interest in Securities of the Issuer

          Item 5 is hereby amended and restated as follows:

     (a) As of the date  hereof,  THEC  beneficially  owns,  and KeySpan and KEC
beneficially  own indirectly  through THEC,  17,380,392  shares of Common Stock,
representing  approximately 55% of the total outstanding  shares of Common Stock
(based on  31,854,155  shares of Common  Stock  outstanding  as  reported in the
Issuer's  Quarterly  Report on Form 10-Q filed with the  Securities and Exchange
Commission  on May 7, 2004).  Upon  consummation  of the  proposed  transactions
described in Item 4, THEC, and KeySpan and KEC indirectly through THEC, will own
6,580,392 shares, or approximately 24%, of Issuer's outstanding Common Stock (or
in the case the  underwriters  exercise  their  over  allotment  option in full,
6,270,392 shares, or approximately 23%, of Issuer's outstanding Common Stock).

     (b) THEC has, and KeySpan and KEC each have  indirectly  through THEC, sole
power to vote or direct the vote and to dispose  or direct  the  disposition  of
shares of Common Stock owned by it.

     (c) Not applicable.

     (d) Not applicable.

     (e) Not applicable.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to
Securities of the Issuer

     Item 6 is hereby amended and restated as follows:



                                                                Page 7 of 12

     Upon consummation of the proposed transactions  described in Item 4, Robert
B. Catell,  the Chief  Executive  Officer of KeySpan and KEC, who also serves as
director  to KeySpan  and KEC,  and  Stephen W.  McKessey,  who also serves as a
director of KeySpan, will serve as directors of Issuer.

     In addition, KeySpan plans to enter into an underwriting agreement pursuant
to which it would agree, among other things, not to transfer,  without the prior
written  consent of the  underwriters  and  subject to certain  exceptions,  any
shares of Common  Stock  during the period  ending 90 days after the date of the
prospectus  supplement  relating to the offering of shares of Common  Stock.  As
part of the  transactions,  THEC would also agree that, upon consummation of the
proposed  transactions  described in Item 4, for a period of three  years,  THEC
would  agree not to increase  its  ownership  interest  in the Issuer  above the
ownership interest it has at the time of consummation.

     Except as described in this Schedule 13D, or in the exhibits  hereto,  none
of KeySpan,  KEC or THEC, nor, to the best knowledge and belief of KeySpan,  KEC
and THEC, any of their respective directors or executive officers, is a party to
any other contract,  arrangement,  understanding or relationship with respect to
any  securities  of the Issuer,  except that Mr.  Cattel and Mr.  McKessey  have
interests in stock  options  granted by the Issuer for  compensation  related to
their service as directors of the Issuer.  Mr.  McKessey also receives an annual
retainer  and meeting  fees  associated  with his  services as a director of the
Issuer.

Item 7. Material to Be Filed as Exhibits

          Item 7 is hereby amended by adding the following text:

          7.   Joint Filing  Agreement,  dated May 25, 2004 among the  Reporting
               Persons  relating to the filing of a joint  statement on Schedule
               13D.

          8.   Press Release, dated May 24, 2004, issued by KeySpan Corporation.





                                                                Page 8 of 12

                                    Signature

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

     Date: May 25, 2004


                                        KEYSPAN CORPORATION

                                        By:    /s/ Michael J. Taunton
                                               ----------------------
                                               Name:  Michael J. Taunton
                                               Title: Senior Vice President
                                                      and Treasurer



                                        KEYSPAN ENERGY CORPORATION

                                        By:    /s/ Michael J. Taunton
                                               ----------------------
                                               Name:  Michael J. Taunton
                                               Title: Senior Vice President
                                                      and Treasurer



                                        THEC HOLDINGS CORP.

                                        By:    /s/ Saiyed Zain Mirza
                                               ---------------------
                                              Name:  Saiyed Zain Mirza
                                              Title: Senior Vice President
                                                     and Chief Financial Officer









                                                                Page 9 of 12

                                    Annex A-1

The name,  position  and  present  principal  occupation  of each  director  and
executive  officer of KeySpan  Corporation  are set forth  below.  The  Business
address for each of the executive officers and directors listed below is KeySpan
Corporation,  One  MetroTech  Center,  Brooklyn,  New York 11201.  All executive
officers and directors listed below are United States citizens.



Name                                  Position                                        Present Principal Occupation
-----                                 --------                                        ----------------------------
                                                                               
Robert B. Catell                      Chairman, Chief Executive Officer and Director  Chairman and Chief Executive Officer of
                                                                                      KeySpan Corporation

Robert J. Fani                        President and Chief Operating Officer           President and Chief Operating Officer of
                                                                                      KeySpan Corporation

Wallace P. Parker, Jr.                President - Energy Delivery and Customer        President - Energy Delivery and Customer
                                      Relations Group                                 Relations Group of KeySpan Corporation

Steven L. Zelkowitz                   President - Energy Assets and Supply Group      President - Energy Assets and Supply Group
                                                                                      of KeySpan Corporation

John A. Caroselli                     Executive Vice President - Strategic Services   Executive Vice President - Strategic
                                                                                      Services of KeySpan Corporation

Gerald Luterman                       Executive Vice President and Chief Financial    Executive Vice President and Chief Financial
                                      Officer                                         Officer of KeySpan Corporation

Anthony Nozzolillo                    Executive Vice President - Electric Operations  Executive Vice President - Electric
                                                                                      Operations of KeySpan Corporation

Lenore F. Puleo                       Executive Vice President - Client Services      Executive Vice President - Client Services
                                                                                      of KeySpan Corporation

Nicholas Stavropoulos                 Executive Vice President - KeySpan Energy       Executive Vice President - KeySpan Energy
                                      Delivery New England                            Delivery New England of KeySpan Corporation

John J. Bishar, Jr.                   Senior Vice President, General Counsel and      Senior Vice President, General Counsel and
                                      Secretary                                       Secretary of KeySpan Corporation

Joseph F. Bodanza                     Senior Vice President and Chief Accounting      Senior Vice President and Chief Accounting
                                      Officer                                         Officer of KeySpan Corporation

Michael J. Taunton                    Senior Vice President and Treasurer             Senior Vice President and Treasurer of
                                                                                      KeySpan Corporation

Theresa A. Balog                      Vice President and Controller                   Vice President and Controller of KeySpan
                                                                                      Corporation

Lawrence Dryer                        Vice President and General Auditor              Vice President and General Auditor of
                                                                                      KeySpan Corporation

Andrea S. Christensen                 Director                                        Partner, Kaye Scholer LLP

Alan H. Fishman                       Director                                        President and Chief Executive Officer,
                                                                                      Independence Community Bank Corp.




                                                                Page 10 of 12

J. Atwood Ives                        Director                                        Former Chairman and Chief Executive
                                                                                      Officer, Eastern

James R. Jones                        Director                                        Chairman and Chief Executive Officer of
                                                                                      Manatt Jones Global Strategies LLP

James L. Larocca                      Director                                        Professor of Public Policy, Long Island
                                                                                      University's Southampton College

Gloria C. Larson                      Director                                        Of Counsel and Co-Chair of the Government
                                                                                      Practices Group, Foley Hoag LLP

Stephen W. McKessy                    Director                                        Retired Vice Chairman, PricewaterhouseCoopers

Edward D. Miller                      Director                                        Member of the Supervisory Board and Senior
                                                                                      Advisor to the Chief Executive Officer, AXA
                                                                                      Group

Vikki L. Pryor                        Director                                        President and Chief Executive Officer, SBLI
                                                                                      Mutual Insurance Company, Inc.








                                                                Page 11 of 12

                                    Annex A-2

The name,  position  and  present  principal  occupation  of each  director  and
executive  officer  of  KeySpan  Energy  Corporation  are set forth  below.  The
Business  address for each of the executive  officers and directors listed below
is KeySpan Energy Corporation,  One MetroTech Center,  Brooklyn, New York 11201.
All executive officers and directors listed below are United States citizens.



Name                                  Position                                        Present Principal Occupation
-----                                 --------                                        ----------------------------
                                                                               
Robert B. Catell                      President, Chief Executive Officer and          Chairman and Chief Executive Officer of
                                      Director                                        KeySpan Corporation

John J. Bishar, Jr.                   Senior Vice President and Secretary             Senior Vice President, General Counsel and
                                                                                      Secretary of KeySpan Corporation

Michael J. Taunton                    Senior Vice President and Treasurer             Senior Vice President and Treasurer of
                                                                                      KeySpan Corporation

Alfred C. Bereche                     Assistant Secretary                             Assistant General Counsel of KeySpan
                                                                                      Corporation

Sandra M. Cano                        Assistant Secretary                             Manager, Corporate Secretary's Office of
                                                                                      KeySpan Corporate Services LLC

Ronald S. Macklin                     Assistant Secretary                             Assistant General Counsel of KeySpan
                                                                                      Corporate Services LLC

Colleen A. Meade                      Assistant Secretary                             Counsel of KeySpan Corporate Services LLC






                                                                Page 12 of 12

                                    Annex A-3

The name,  position  and  present  principal  occupation  of each  director  and
executive  officer of THEC are set forth below. The Business address for each of
the executive  officers and directors  listed below is THEC Holding  Corp.,  One
MetroTech Center, Brooklyn, New York 11201. All executive officers and directors
listed  below are United  States  citizens,  except for H. Neil Nichols who is a
Canadian citizen with work permit.



Name                                   Position                                        Present Principal Occupation
-----                                  --------                                        ----------------------------
                                                                                
H. Neil Nichols                        President and Director                          President, KeySpan Energy Development
                                                                                       Corporation
S. Zain Mirza                          Senior Vice President,
                                       Chief Financial Officer and Director            Senior Vice President, KeySpan Energy
                                                                                       Development Corporation

John J. Bishar, Jr.                    Senior Vice President and Secretary             Senior Vice President, General Counsel and
                                                                                       Secretary of KeySpan Corporation

Michael J. Nilsen                      Vice President, Treasurer, Comptroller and      Vice President - Finance, KeySpan Energy
                                       Director                                        Development Corporation

Alfred C. Bereche                      Vice President and Assistant Secretary          Assistant General Counsel of KeySpan
                                                                                       Corporation

Sandra M. Cano                         Assistant Secretary                             Manager, Corporate Secretary's Office of
                                                                                       KeySpan Corporate Services LLC

Colleen A. Meade                       Assistant Secretary                             Counsel of KeySpan Corporate Services LLC







                                INDEX OF EXHIBITS

Number                   Description

7                          Joint Filing Agreement, dated May 25, 2004, among the
                           Reporting Persons relating to  the filing of a joint
                           statement on Schedule 13D.

8                          Press Release, dated May 24, 2004, issued by KeySpan
                           Corporation.













                                                                      Exhibit 7


                             JOINT FILING AGREEMENT


     In accordance with Rule 13d-1(k)  promulgated under the Securities Exchange
Act of 1934, as amended,  the undersigned  hereby agree to the joint filing with
all  other  Reporting  Persons  (as such term is  defined  in the  Schedule  13D
referred  to below) on behalf of each of them of a  Statement  on  Schedule  13D
(including amendments thereto) with respect to the Common Stock, par value $0.01
per share, of The Houston Exploration Company, a Delaware corporation,  and that
this  Agreement  may be  included  as an  Exhibit  to such  joint  filing.  This
Agreement may be executed in any number of  counterparts,  all of which together
shall constitute one and the same instrument.


     IN WITNESS WHEREOF, the undersigned hereby execute this Agreement as of the
25th day of May 2004.

                                       KEYSPAN CORPORATION

                                       By:  /s/ Michael J. Taunton
                                            ----------------------
                                            Name:  Michael J. Taunton
                                            Title: Senior Vice President
                                                   and Treasurer



                                       KEYSPAN ENERGY CORPORATION

                                       By:  /s/ Michael J. Taunton
                                            ----------------------
                                            Name:  Michael J. Taunton
                                            Title: Senior Vice President
                                                   and Treasurer



                                       THEC HOLDINGS CORP.

                                       By:  /s/ Saiyed Zain Mirza
                                            ---------------------
                                            Name:  Saiyed Zain Mirza
                                            Title: Senior Vice President
                                                   and Chief Financial Officer






                                                                      Exhibit 8

     Press  Release,  dated May 24,  2004,  issued  by  KeySpan  Corporation  is
attached.






                                                                    NEWS
--------------------------------------------------------------------------------
KeySpan Corporation                                        For Immediate Release


Contacts:  Investors                                     Media Relations
           George Laskaris                               Andrea Staub
           718.403.2526                                  516.545.5052
                                                         516.824.1241 (pager)


      KeySpan Reduces its Ownership in Houston Exploration from 55% to 24%
            through an Exchange for a Houston Exploration Subsidiary

KeySpan Corporation  (NYSE:KSE)  announced today that the company plans to enter
into an agreement with The Houston  Exploration  Company  (NYSE:THX) under which
KeySpan will  transfer to Houston  Exploration  10.8  million  shares of Houston
Exploration  common  stock  in  exchange  for  100% of a  wholly  owned  Houston
Exploration  subsidiary,  Seneca-Upshur  Petroleum,  Inc.  At  the  time  of the
exchange,  the  subsidiary  will hold all of Houston  Exploration's  Appalachian
Basin assets and an amount of additional  cash  calculated so as to equalize the
value  of the  operating  business  and the  Houston  Exploration  shares  being
exchanged.

The transaction is consistent  with the business  strategies of both KeySpan and
Houston Exploration. As previously discussed,  KeySpan does not consider Houston
Exploration to be a strategic  holding and has been working to  restructure  its
stake in the company in a manner  that will be  beneficial  to both  KeySpan and
Houston Exploration.

"This transaction  represents an important step to restructuring our interest in
Houston Exploration. We welcome Seneca-Upshur into the KeySpan family and intend
to grow this business  through  additional  investments in energy related assets
that support our core businesses," said Robert B. Catell, KeySpan's Chairman and
Chief  Executive  Officer.  "This  transaction  allows  the  Company  to further
concentrate on executing its strategy of growing its core energy businesses."

The  parties  have  ascribed a value of $60 million  dollars to the  Appalachian
Basin  producing  assets.  At December 31,  2003,  these  properties  had proved
reserves  of 50.5  billion  cubic  feet of natural  gas  equivalent  (Bcfe),  or
approximately  7 percent of Houston  Exploration's  total proved  reserves.  The
Appalachian  assets  include  properties  originally  acquired  and  owned  by a
predecessor  company to KeySpan in the early 1970's to strengthen its gas supply
strategy. At the time of the transaction, it is expected that Seneca-Upshur will
have  cash in  excess  of $350  million  based  on the  initial  offering  price





assumptions set forth below.  This KeySpan  subsidiary  plans to use the cash to
make additional investments in energy related assets.

Of the 10.8  million  shares that  Houston  Exploration  expects to receive from
KeySpan,  Houston Exploration intends to retire approximately 4.6 million shares
and plans to offer 6.2 million shares of common stock in a public offering.

The value of the exchange  will be dependent  on the  ultimate  public  offering
price of the Houston  Exploration  shares in the  offering.  Assuming an initial
public  offering  price of $45.01 (which is the May 21,2004,  NYSE last sale for
Houston  Exploration),  KeySpan  will receive a per share value equal to $40.09,
before  expenses.  The value per share  received  by KeySpan  will  increase  or
decrease,  as  the  case  may  be,  by  approximately  $0.51  per  share  for  a
corresponding  $1.00 increase or decrease in the public offering price of $45.01
per share.

This transaction will reduce KeySpan's ownership interest in Houston Exploration
to  approximately  24% from the current 55% level with the number of outstanding
shares being reduced from approximately 17.4 million shares to approximately 6.6
million shares. In addition, three of KeySpan's five designated directors on the
Houston  Exploration  Board will resign at the closing of the  transaction,  and
KeySpan will retain the right to nominate two of the remaining  seven  directors
on the Houston Exploration Board.

Consummation of this  transaction is subject to each party's  satisfaction  with
the public  offering  price.  Accordingly,  no  assurance  can be given that the
transaction  will be completed.  The  underwriters  will be granted an option to
purchase  an   additional   930,000   shares  of  common   stock  to  cover  any
over-allotments.   If  this  over-allotment  is  exercised  in  full,  KeySpan's
ownership  interest  in Houston  Exploration  will be  reduced to  approximately
22.5%.

This press release shall not constitute an offer to sell or the  solicitation of
an offer to buy nor shall there be any sale of these  securities in any state in
which such offer,  solicitation  or sale would be unlawful prior to registration
or qualification under the securities law of any state.
--------------------------------------------------------------------------------

A member of the Standard & Poor's 500 Index,  KeySpan Corporation  (NYSE:KSE) is
the fifth  largest  distributor  of  natural  gas in the  United  States and the
largest  in the  Northeast,  operating  regulated  gas  utilities  in New  York,
Massachusetts  and  New  Hampshire,   serving  2.5  million   customers.   These
customer-focused businesses are complemented by a portfolio of service companies
which  offer  energy-related  products,  services  and  solutions  to homes  and
businesses. KeySpan is also the largest electric generator in New York State. We
own approximately 6,600 megawatts of generating capacity, providing power to 1.1
million  customers  of the  Long  Island  Power  Authority  on Long  Island  and
supplying  approximately  25  percent  of New York  City's  capacity  needs.  In
addition to these  assets,  KeySpan  has  strategic  investments  in natural gas
exploration, production, pipeline transportation,  distribution and storage, and
Canadian gas processing.  KeySpan has headquarters in Brooklyn,  New England and
Long   Island.   For   more   information,   visit   KeySpan's   web   site   at
www.keyspanenergy.com.

Certain  statements  contained  herein  are  forward-looking  statements,  which
reflect  numerous  assumptions  and  estimates and involve a number of risks and
uncertainties.  For these statements, we claim the protection of the safe harbor
for  forward-looking  statements  provided by the Private Securities  Litigation
Reform Act of 1995. There are possible  developments that could cause our actual
results  to  differ   materially   from  those   forecast   or  implied  in  the
forward-looking  statements.  You are cautioned  not to place undue  reliance on
these forward-looking statements,  which are current only as of the date of this
filing.  We  disclaim  any  intention  or  obligation  to update  or revise  any
forward-looking  statements,  whether  as a result  of new  information,  future
events or otherwise. Among the factors that could cause actual results to differ
materially are: general economic conditions,  especially in the Northeast United
States;  available  sources and costs of fuel;  volatility of energy prices in a
deregulated  market environment as well as in the source of natural gas and fuel
used to generate electricity;  potential write-down of our investment in natural
gas properties  when natural gas prices are depressed or if we have  significant
downward  revisions  in our  estimated  proved gas  reserves;  federal and state
regulatory  initiatives that increase competition,  threaten cost and investment
recovery and impact rate structure;  our ability to successfully reduce our cost
structures;  implementation of new accounting standards;  the degree to which we
develop unregulated  business ventures,  as well as federal and state regulatory
policies  affecting our ability to retain and operate those  business  ventures;
our  ability to identify  and make  complementary  acquisitions,  as well as the
successful  integration of those acquisitions;  inflationary trends and interest
rates; and risks detailed from time to time in reports and other documents filed
by us with the Securities and Exchange Commission.

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