SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549



                                  SCHEDULE 13G
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934


                           DAWSON GEOPHYSICAL COMPANY
             ------------------------------------------------------
                                (Name of Issuer)


                                  COMMON STOCK
             ------------------------------------------------------
                         (Title of Class of Securities)


                                    239359102
             ------------------------------------------------------
                                 (CUSIP NUMBER)




                                  April 8, 2005
             ------------------------------------------------------
             (Date of event which requires filing of this statement)

     Check the appropriate box to designate the rule pursuant to which this
Schedule is filed:

[ ]  Rule 13d-1(b)

[X]  Rule 13d-1(c)

[ ]  Rule 13d-1(d)


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 the
disclosures provided in a prior cover page.

The information required in 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 1 of 16 Pages


CUSIP No. 239359102 13G Page 2 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Rubicon Master Fund - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4)) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** OO - -------------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 239359102 13G Page 3 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Rubicon Fund Management Ltd. - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** OO - -------------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 239359102 13G Page 4 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Rubicon Fund Management LLP - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United Kingdom - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** OO - -------------------------------------------------------------------------------- ** SEE INSTRUCTIONS BEFORE FILLING OUT!

CUSIP No. 239359102 13G Page 5 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Paul Anthony Brewer - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United Kingdom - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 6 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Jeffrey Eugene Brummette - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 7 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) William Francis Callanan - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 8 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Vilas Gadkari - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 9 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Robert Michael Greenshields - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United Kingdom - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 10 of 16 Pages - -------------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY) Horace Joseph Leitch III - -------------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP ** (a) [ ] (b) [X] - -------------------------------------------------------------------------------- (3) SEC USE ONLY - -------------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION United States - -------------------------------------------------------------------------------- NUMBER OF (5) SOLE VOTING POWER -0- SHARES - -------------------------------------------------------------------------------- BENEFICIALLY (6) SHARED VOTING POWER 435,000 (see Item 4) OWNED BY - -------------------------------------------------------------------------------- EACH (7) SOLE DISPOSITIVE POWER -0- REPORTING - -------------------------------------------------------------------------------- PERSON WITH (8) SHARED DISPOSITIVE POWER 435,000 (see Item 4) - -------------------------------------------------------------------------------- (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 435,000 (see Item 4) - -------------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES ** [ ] - -------------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.8% - -------------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON ** IN - --------------------------------------------------------------------------------

CUSIP No. 239359102 13G Page 11 of 16 Pages Item 1. (a) Name of Issuer Dawson Geophysical Company, a Texas corporation (the "Company"). (b) Address of Issuer's Principal Executive Offices: 508 West Wall, Suite 800 Midland, Texas 79701 Item 2(a). Name of Person Filing This statement is filed by (i) Rubicon Master Fund; (ii) Rubicon Fund Management Ltd., with respect to shares beneficially owned by Rubicon Master Fund; (iii) Rubicon Fund Management LLP, with respect to shares beneficially owned by Rubicon Master Fund; (iv) Paul Anthony Brewer, with respect to shares beneficially owned by Rubicon Master Fund; (v) Jeffrey Eugene Brummette, with respect to shares beneficially owned by Rubicon Master Fund; (vi) William Francis Callanan with respect to shares beneficially owned by Rubicon Master Fund; (vii) Vilas Gadkari with respect to shares beneficially owned by Rubicon Master Fund; (viii) Robert Michael Greenshields, with respect to shares beneficially owned by Rubicon Master Fund; and (ix) Horace Joseph Leitch III, with respect to shares beneficially owned by Rubicon Master Fund. Item 2(b). Address of Principal Business Office The address of (i) Rubicon Master Fund is P.O. Box 309, Ugland House, George Town, Cayman Islands, (ii) Rubicon Fund Management Ltd. is P.O. Box 309, Ugland House, George Town, Cayman Islands, (iii) Rubicon Fund Management LLP is 103 Mount St., London W1K2TJ, United Kingdom and (iv) each of the individuals is 103 Mount St., London W1K2TJ, United Kingdom. Item 2(c) Citizenship Rubicon Master Fund and Rubicon Fund Management Ltd. are companies organized under the laws of the Cayman Islands. Rubicon Fund Management LLP is a Limited Liability Partnership organized under the laws of the United Kingdom. Jeffrey Eugene Brummette, William Francis Callanan, Vilas Gadkari and Horace Joseph Leitch III are citizens of the United States. Paul Anthony Brewer and Robert Michael Greenshields are citizens of the United Kingdom. (d) Title of Class of Securities Common Stock, $.33-1/3 par value ("Common Stock") (e) CUSIP Number 239359102 Item 3. Not applicable Item 4. Ownership (a) Amount Beneficially Owned The percentages used herein are calculated based upon the 7,442,794 shares of Common Stock issued and outstanding as of March 1, 2005 as reported in the Company's prospectus (File No: 33-121236) filed pursuant to Rule 424(b)(4) with the Securities and Exchange Commission on March 1, 2005.

CUSIP No. 239359102 13G Page 12 of 16 Pages As of the close of business on April 18, 2005 1. Rubicon Master Fund (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 2. Rubicon Fund Management Ltd. (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 3. Rubicon Fund Management LLP (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 4. Paul Anthony Brewer (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 5. Jeffrey Eugene Brummette (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 6. William Francis Callanan (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000

CUSIP No. 239359102 13G Page 13 of 16 Pages 7. Vilas Gadkari (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 8. Robert Michael Greenshields (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 9. Horace Joseph Leitch III (a) Amount beneficially owned: 435,000 (b) Percent of class: 5.8% (c) (i) Sole power to vote or direct the vote: -0- (ii) Shared power to vote or direct the vote 435,000 (iii) Sole power to dispose or direct the disposition: -0- (iv) Shared power to dispose or direct the disposition: 435,000 Rubicon Fund Management Ltd., Rubicon Fund Management LLP, Paul Anthony Brewer, Jeffrey Eugene Brummette, William Francis Callanan, Vilas Gadkari, Robert Michael Greenshields and Horace Joseph Leitch III, own directly no shares of Common Stock. Pursuant to Investment Agreements, each of Rubicon Fund Management Ltd., and Rubicon Fund Management LLP share all investment and voting power with respect to the Securities held by Rubicon Master Fund. By reason of the provisions of Rule 13D-3 of the Securities Exchange Act of 1934, as amended, each of Rubicon Fund Management Ltd., Rubicon Fund Management LLP, Paul Anthony Brewer, Jeffrey Eugene Brummette, William Francis Callanan, Vilas Gadkari, Robert Michael Greenshields and Horace Joseph Leitch III may be deemed to own beneficially 435,000 shares of Common Stock (constituting approximately 5.8% of Common Stock outstanding). Each of Rubicon Fund Management Ltd., Rubicon Fund Management LLP, Paul Anthony Brewer, Jeffrey Eugene Brummette, William Francis Callanan, Vilas Gadkari, Robert Michael Greenshields and Horace Joseph Leitch III disclaim beneficial ownership of any securities covered by this statement. 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.

CUSIP No. 239359102 13G Page 14 of 16 Pages Item 8. Identification and Classification of Members of the Group This statement is filed by: Not Applicable Item 9. Notice of Dissolution of Group Not applicable Item 10. Certification By signing below each of the undersigned certifies that, to the best of its knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

CUSIP No. 239359102 13G Page 15 of 16 Pages SIGNATURE After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information with respect to it set forth in this statement is true, complete, and correct. Dated: April 19, 2005 RUBICON MASTER FUND By: /s/ DAVID DEROSA ---------------- Name: David DeRosa Title: Authorized Person RUBICON FUND MANAGEMENT LTD. By: /s/ DAVID DEROSA ---------------- Name: David DeRosa Title: Authorized Person RUBICON FUND MANAGEMENT LLP By: /s/ HORACE JOSEPH LEITCH III ---------------------------- Name: Horace Joseph Leitch III Title: Authorized Person PAUL ANTHONY BREWER By: /s/ PAUL ANTHONY BREWER ----------------------- Name: Paul Anthony Brewer JEFFREY EUGENE BRUMMETTE By: /s/ JEFFREY EUGENE BRUMMETTE ---------------------------- Name: Jeffrey Eugene Brummette WILLIAM FRANCIS CALLANAN By: /s/ WILLIAM FRANCIS CALLANAN ---------------------------- Name: William Francis Callanan

CUSIP No. 239359102 13G Page 16 of 16 Pages VILAS GADKARI By: /s/ VILAS GADKARI ----------------- Name: Vilas Gadkari ROBERT MICHAEL GREENSHIELDS By: /s/ ROBERT MICHAEL GREENSHIELDS ------------------------------- Name: Robert Michael Greenshields HORACE JOSEPH LEITCH III By: /s/ HORACE JOSEPH LEITCH III ---------------------------- Name: Horace Joseph Leitch III