Exhibit 4.5 SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ______________________ FORM 8-A FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(B) OR (G) OF THE SECURITIES EXCHANGE ACT OF 1934 ________________________ MALLINCKRODT GROUP INC. (formerly known as IMCERA Group Inc.) (Exact name of registrant as specified in its charter) NEW YORK 36-1263901 (State of incorporation or organization) (IRS employer identification number) 7733 FORSYTH BOULEVARD, ST. LOUIS, MISSOURI 63105 (Address of principal executive offices) (Zip Code) SECURITIES TO BE REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT - ------------------------------------------------------------------------------- Title of each class Name of each exchange on which to be so registered each class is to be registered - ------------------------------------------------------------------------------- - ------------------------------------------------------------------------------- 6% Notes due October 15, 2003 New York Stock Exchange, Incorporated - ------------------------------------------------------------------------------- 7% Debentures due December 15, 2013 New York Stock Exchange, Incorporated - ------------------------------------------------------------------------------- SECURITIES TO BE REGISTERED PURSUANT TO SECTION 12(G) OF THE ACT None Item 1. Description of Registrant's Securities to be Registered. On April 27, 1992, Registration Statement No. 33-47081 on Form S-3 of Mallinckrodt Group Inc., formerly known as IMCERA Group Inc. (the "Company"), a New York corporation, relating to $250,000,000 of Debt Securities, was declared effective. (a) $100,000,000 AGGREGATE PRINCIPAL AMOUNT OF 6% NOTES DUE OCTOBER 15, 2003 (THE "NOTES") OF THE COMPANY. The Company issued a Prospectus, dated October 12, 1993, as supplemented by Prospectus Supplement dated October 19, 1993, pursuant to the aforementioned Registration Statement, relating to the Notes. The information set forth under the caption "Description of the Securities" in such Prospectus and under the caption "Description of the Notes" in such Prospectus Supplement is incorporated herein by reference. (b) $100,000,000 AGGREGATE PRINCIPAL AMOUNT OF 7% DEBENTURES DUE DECEMBER 15, 2013 (THE "DEBENTURES") OF THE COMPANY. The Company issued a Prospectus, dated December 1, 1993, as supplemented by Prospectus Supplement dated December 8, 1993, pursuant to the aforementioned Registration Statement, relating to the Debentures. The information set forth under the caption "Description of the Securities" in such Prospectus and under the caption "Description of the Debentures" in such Prospectus Supplement is incorporated herein by reference. Item 2. Exhibits Exhibit Number 4.1 Form of Indenture dated as of March 15, 1985 between the Company and Morgan Guaranty Trust Company of New York, as Trustee, including Form of Securities (incorporated by reference to Registration Statement No. 2-96566) 4.2 Form of First Supplemental Indenture dated as of April 1, 1992, to Indenture dated March 15, 1985 (incorporated by reference to Registration Statement No. 33-47081) 4.3 Specimen 6% Note due October 15, 2003 4.4 Specimen 7% Debenture due December 15, 2013 -2- Signature Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized. MALLINCKRODT GROUP INC. By/s/ WILLIAM B. STONE ------------------------------------- Name: William B. Stone Title: Vice-President and Controller Date: May 6, 1994 -3- EXHIBIT INDEX Sequentially Exhibit Numbered Number Description Page - ------- ----------- ------------ 4.1 Form of Indenture dated as of March 15, 1985 between the Company and Morgan Guaranty Trust Company of New York, as Trustee, including Form of Securities (incorporated by reference to Registration Statement No. 2-96566) 4.2 Form of First Supplemental Indenture dated as of April 1, 1992, to Indenture dated March 15, 1985 (incorporated by reference to Registration Statement No. 33-47081) 4.3 Specimen 6% Note due October 15, 2003 4.4 Specimen 7% Debenture due December 15, 2013 -4-