UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 T.G.C. INDUSTRIES INC. (TGE) (Name of Issuer) Common Stock (Title of Class of Securities) 872417308 (CUSIP Number) ________________________________________________________________________________ 1) Names of Reporting Persons, IRS Identification Nos. of Above Persons: OTR - Nominee Name for The State Teachers Retirement Board of Ohio, 31-1312155 ________________________________________________________________________________ 2) Check the appropriate box if a member of a group* (a) [_] (b) [_] ________________________________________________________________________________ 3) SEC Use Only ________________________________________________________________________________ 4) Citizenship or Place of Organization Columbus, Ohio ________________________________________________________________________________ Number of Shares Beneficially Owned by Each Reporting Person With 5) Sole Voting Power 740000 6) Shared Voting Power 0 7) Sole Dispositive Power 740000 8) Shared Dispositive Power 0 ________________________________________________________________________________ 9) Aggregate Amount Beneficially Owned by Each Reporting Person 740000 ________________________________________________________________________________ 10) Check if the Aggregate Amount in Row (9) Excludes Certain Shares* [_] ________________________________________________________________________________ 11) Percent of Class Represented by Amount in Row (9) 5.09% ________________________________________________________________________________ 12) Type of Reporting Person* EP ________________________________________________________________________________ SCHEDULE 13G ________________________________________________________________________________ Item 1 (a) Name of Issuer This Statement on Schedule 13G relates to the shares of Instrument T.G.C. INDUSTRIES INC. (b) Address of Issuer's Principal Executive Offices: 1304 Summit Ave, Suite 2 Plano, TX 75074 ________________________________________________________________________________ Item 2 (a) Name of Person Filing: This Statement is filed by OTR - Nominee Name for The State Teachers Retirement Board of Ohio (b) Address of Principal Business Office: The business address of OTR - Nominee Name for The State Teachers Retirement Board of Ohio is 275 East Broad Street Columbus, Ohio 43215 (c) Citizenship: Not Applicable (d) Title of Class of Securities: The securities are shares of a Common Stock. (e) CUSIP No.: The CUSIP Number for the investment is 872417308. ________________________________________________________________________________ Item 3 Type of Person Filing: STRS is an employee benefit plan established for teachers of the public schools of Ohio to provide retirement allowances and other benefits under the terms of Chapter 3307 of the Ohio Revised Code. ________________________________________________________________________________ Item 4 OWNERSHIP (a) Amount Beneficially Owned: STRS owns 740000 shares of T.G.C. INDUSTRIES INC. (b) Percent of Class: STRS believes that there are presently 14547000 outstanding shares of T.G.C. INDUSTRIES INC.; therefore, STRS' ownership of 740000 shares of T.G.C. INDUSTRIES INC. Common Stock is 5.09 percent of this class. (c) Number of Shares As To Which Such Person Has Power: (i) Sole power to vote or to direct the vote 740000 (ii) Shared power to vote or to direct the vote 0 (iii) Sole power to dispose or to direct the disposition of 740000 (iv) Shared power to dispose or to direct the disposition of 0 shares of T.G.C. INDUSTRIES INC. Common stock. ________________________________________________________________________________ Item 5 OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS. If this statements 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 (5) percent of the class of securities, check the following [ ]. ________________________________________________________________________________ Item 6 OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON Not Applicable ________________________________________________________________________________ Item 7 IDENTIFICATION AND CLASSIFICATION OF 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 ________________________________________________________________________________ Item 10 CERTIFICATION By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired in the ordinary course of business and were not acquired for the purpose of, and do not have the effect of, changing or influencing the control of the issuer of such securities, and were not acquired in connection with, or as a participant in, any transaction having such purposes or effect. ________________________________________________________________________________ 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: 01/30/2006 OTR - Nominee Name for The State Teachers Retirement Board of Ohio 275 East Broad Street Columbus, Ohio 43215 STEPHEN A. MITCHELL /s/Stephen A. Mitchell ............................................ Stephen A. Mitchell Deputy Executive Director, Investments 614-227-4003