SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 SCHEDULE 13G (Amendment No. 1) Under the Securities Exchange Act of 1934* Lexicon Genetics Incorporated ----------------------------- (Name of Issuer) Common Stock, $0.001 par value per share ---------------------------------------- (Title of Class of Securities) 528872 10 4 ----------- (CUSIP Number) February 14, 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. CUSIP No. 528872 10 4 Page 2 of 6 -------------------------------------------------------------------------------- 1 NAME OF REPORTING PERSON S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY) Acqua Wellington Opportunity I Limited -------------------------------------------------------------------------------- 2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP* (a) [ ] (b) [ ] -------------------------------------------------------------------------------- 3 SEC USE ONLY -------------------------------------------------------------------------------- 4 CITIZENSHIP OR PLACE OF ORGANIZATION Bahamas -------------------------------------------------------------------------------- NUMBER OF 5 SOLE VOTING POWER SHARES BENEFICIALLY 1,815,000 OWNED BY ---------------------------------------------------- EACH 6 SHARED VOTING POWER REPORTING PERSON 0 WITH ---------------------------------------------------- 7 SOLE DISPOSITIVE POWER 1,815,000 ---------------------------------------------------- 8 SHARED DISPOSITIVE POWER 0 -------------------------------------------------------------------------------- 9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 1,815,000 -------------------------------------------------------------------------------- 10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES* [ ] -------------------------------------------------------------------------------- 11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 2.9% -------------------------------------------------------------------------------- 12 TYPE OF REPORTING PERSON* OO (A corporation organized under the laws of the Bahamas) -------------------------------------------------------------------------------- *SEE INSTRUCTIONS BEFORE FILLING OUT! CUSIP No. 528872 10 4 Page 3 of 6 -------------------------------------------------------------------------------- Item 1. (a) Name of Issuer: Lexicon Genetics Incorporated (b) Address of Issuer's Principal Executive Offices: 8800 Technology Forest Place The Woodlands, Texas 77381 Item 2. (a) Name of Person Filing: Acqua Wellington Opportunity I Limited (b) Address of Principal Business Office or, if none, Residence: Acqua Wellington Opportunity I Limited Shirlaw House 87 Shirley Street P.O. Box SS-19084 Nassau, Bahamas (c) Citizenship: Bahamas (d) Title of Class of Securities: Common Stock, $0.001 par value per share (e) CUSIP Number: 528872 10 4 CUSIP No. 528872 10 4 Page 4 of 6 -------------------------------------------------------------------------------- Item 3. If this statement is filed pursuant to ss.ss.240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: Not applicable. Item 4. Ownership. The following is information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1. (a) Amount beneficially owned: 1,815,000 (b) Percent of class: 2.9% (c) Number of shares as to which the person has: (i) Sole power to vote or to direct the vote: 1,815,000 (ii) Shared power to vote or to direct the vote: 0 (iii) Sole power to dispose or to direct the disposition of: 1,815,000 (iv) Shared power to dispose or to direct the disposition of: 0 Item 5. Ownership of Five Percent or Less of a Class If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [X]. 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. CUSIP No. 528872 10 4 Page 5 of 6 -------------------------------------------------------------------------------- Item 10. Certification Certification pursuant to ss.240.13d-1(c): By signing below I certify that, to the best of my 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. 528872 10 4 Page 6 of 6 -------------------------------------------------------------------------------- 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, complete and correct. Dated: April 14, 2005 ACQUA WELLINGTON OPPORTUNITY I LIMITED By: /s/ Dayrrl Butler ------------------------------------- Name: Dayrrl Butler Title: Director and Vice President