UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                  SCHEDULE 13D

                   Under the Securities Exchange Act of 1934

                                (Amendment No. 12)*



                          AEOLUS PHARMACEUTICALS, INC.
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                                (Name of Issuer)

                     Common Stock, par value $0.01 per share
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                         (Title of Class of Securities)

                                   45325S-10-1
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                                 (CUSIP Number)

                                  Mary L. King
                         Xmark Opportunity Partners, LLC
                           90 Grove Street, Suite 201
                              Ridgefield, CT 06877
                                 (646) 688-5728
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                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                December 6, 2007
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             (Date of Event which Requires Filing of this Statement)


If the filing person has previously  filed a statement on Schedule l3G 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).





Cusip No.       45325S-10-1
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1.  Names of Reporting Persons.  I.R.S. Identification Nos. of above persons
    (entities only):
               Xmark Opportunity Partners, LLC
               20-2052197
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2.  Check the Appropriate Box if a Member of a Group (See Instructions):
         (a)   Not
         (b)   Applicable
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3.  SEC Use Only

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4.  Source of Funds (See Instructions):  AF, WC
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5.  Check if Disclosure  of Legal Proceedings Is Required Pursuant to Items 2(d)
    or 2(e):               Not Applicable
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6.  Citizenship or Place of Organization:    United States

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    Number of                      7. Sole Voting Power:             15,153,155*
                                     -------------------------------------------
    Shares Beneficially            8. Shared Voting Power:
                                     -------------------------------------------
    Owned by
    Each Reporting                 9. Sole Dispositive Power:        14,153,155*
                                      ------------------------------------------
    Person With                    10. Shared Dispositive Power:
                                      ------------------------------------------
--------------------------------------------------------------------------------
11. Aggregate Amount Beneficially Owned by Each Reporting Person:   15,153,155*

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12. Check if  the Aggregate  Amount in  Row (11) Excludes  Certain  Shares  (See
    Instructions):         Not Applicable
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13. Percent of Class Represented by Amount in Row (11):   44.4%*
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14. Type of Reporting Person (See Instructions):  IA
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* Xmark Opportunity Partners, LLC ("Opportunity Partners") is the sole member of
the  investment  manager of Xmark  Opportunity  Fund,  L.P., a Delaware  limited
partnership  ("Opportunity  LP"),  and Xmark  Opportunity  Fund,  Ltd., a Cayman
Islands exempted company ("Opportunity Ltd"), and, as such, possesses sole power
to vote and direct the disposition of all securities of Aeolus  Pharmaceuticals,
Inc.,  a  Delaware  corporation  (the  "Company"),  held by  Opportunity  LP and
Opportunity  Ltd.  Opportunity  Partners is the  investment  manager of Xmark JV
Investment Partners,  LLC, a Delaware limited liability company ("JV Partners"),
and, as such,  possesses  sole power to vote and direct the  disposition  of all
securities of the Company held by JV Partners.  Opportunity Partners is the sole
manager  of  Goodnow  Capital,  L.L.C.,  a Delaware  limited  liability  company
("Goodnow"),  and,  as  such,  possesses  sole  power  to vote  and  direct  the
disposition of all  securities of the Company held by Goodnow.  Mitchell D. Kaye
and David C. Cavalier,  the Chief Executive Officer and Chief Operating Officer,
respectively, of Xmark Capital Partners, LLC, the Managing Member of Opportunity
Partners,  share  voting and  investment  power with  respect to all  securities
beneficially owned by Opportunity Partners.






As of December 6, 2007,  Opportunity LP held 2,959,378 common shares,  $0.01 par
value per share (the "Common Shares"), of the Company,  which includes 1,276,435
Common  Shares of the Company  owned by Goodnow,  and warrants to purchase up to
660,000 Common Shares of the Company at an exercise price of $0.50 per share. As
of  December  6,  2007,  Opportunity  Ltd held  6,140,095  Common  Shares of the
Company, which includes 3,300,653 Common Shares of the Company owned by Goodnow,
and  warrants  to  purchase  up to 990,000  Common  Shares of the  Company at an
exercise  price of $0.50 per share.  As of  December 6, 2007,  JV Partners  held
1,023,731  Common  Shares of the Company and  warrants to purchase up to 500,000
Common Shares of the Company at an exercise price of $0.50 per share. All of the
warrants held by Opportunity LP, Opportunity Ltd and JV Partners are exercisable
within 60 days of the date of event which  required the filing of this Amendment
No. 9 to Schedule  13D. As of December 6, 2007,  Goodnow held  3,529,951  Common
Shares of the Company in addition to the Common Shares of the Company referenced
above.  As of  December  6,  2007,  Opportunity  Partners  had the right to vote
1,000,000  Common  Shares of the Company  pursuant to a voting  trust  agreement
between  Opportunity  Partners  and the holders of record of the  shares.  As of
December 6, 2007,  David C. Cavalier  held 100,000  Common Shares of the Company
issuable upon the exercise of options held by Mr. Cavalier.

Based upon  information  set forth in the Company's most recent Annual Report on
Form 10-K, as filed with the Securities and Exchange  Commission on December 13,
2007, there were 31,952,749  Common Shares of the Company issued and outstanding
as of December  10,  2007.  As a result of the  foregoing,  for purposes of Reg.
Section 240.13d-3, Opportunity Partners is deemed to beneficially own 15,153,155
Common  Shares of the  Company,  or 44.4% of the  Common  Shares of the  Company
deemed issued and outstanding as of December 6, 2007.









Item 1.   Security and Issuer.
          -------------------

          No material change.


Item 2.   Identity and Background.
          ------------------------

          No material change.


Item 3.   Source and Amount of Funds or Other Consideration.
          -------------------------------------------------

          This Item 3 is hereby  further  amended by adding the following at the
end thereof:

          "See Item 5 for further information."


Item 4.   Purpose of Transaction.
          -----------------------

          No material change.


Item 5.   Interest in Securities of the Issuer.
          ------------------------------------

          This Item 5 is hereby  amended and restated to read in its entirety as
follows:

          "Based upon  information set forth in the Company's most recent Annual
Report on Form 10-K,  as filed with the  Securities  and Exchange  Commission on
December 13, 2007, there were 31,952,749 Common Shares of the Company issued and
outstanding as of December 10, 2007.

          As of December 6, 2007,  Opportunity LP held 2,959,378  common shares,
$0.01 par value per share (the "Common Shares"), of the Company,  which includes
1,276,435  Common  Shares of the  Company  owned by  Goodnow,  and  warrants  to
purchase up to 660,000  Common  Shares of the  Company at an  exercise  price of
$0.50 per share. As of December 6, 2007,  Opportunity Ltd held 6,140,095  Common
Shares of the Company,  which  includes  3,300,653  Common Shares of the Company
owned by Goodnow,  and warrants to purchase up to 990,000  Common  Shares of the
Company at an exercise  price of $0.50 per share.  As of  December  6, 2007,  JV
Partners held 1,023,731 Common Shares of the Company and warrants to purchase up
to 500,000 Common Shares of the Company at an exercise price of $0.50 per share.
All of the warrants held by Opportunity LP,  Opportunity Ltd and JV Partners are
exercisable  within 60 days of the date of event  which  required  the filing of
this  Amendment  No. 9 to Schedule  13D. As of  December 6, 2007,  Goodnow  held
3,529,951  Common  Shares of the Company in addition to the Common Shares of the
Company referenced above. As of December 6, 2007,  Opportunity  Partners had the
right to vote 1,000,000  Common Shares of the Company pursuant to a voting trust
agreement between Opportunity Partners and the holders of record of the shares.

          Opportunity  Partners  possesses  sole  power to vote and  direct  the
disposition  of all  securities  of the Company  held by the Funds and  Goodnow.
Messrs.  Kaye and Cavalier share voting and investment power with respect to all
securities  beneficially owned by Opportunity  Partners. As of December 6, 2007,
Mr. Cavalier held 100,000 Common Shares of the Company issuable upon exercise of
options held by Mr. Cavalier.





          As a result of the foregoing,  for purposes of Reg. Section 240.13d-3,
Opportunity  Partners is deemed to beneficially own 15,153,155  Common Shares of
the  Company,  or 44.4% of the Common  Shares of the Company  deemed  issued and
outstanding as of December 6, 2007.

          Since the date of event  that  required  the  filing of  Schedule  13D
Amendment  No. 11  (October  29,  2007) to December  6, 2007,  the  below-listed
transactions in the Common Shares of the Company, or securities  exercisable for
Common Shares of the Company,  were consummated by persons referenced in Item 2.
More specifically,  all of the below-listed transactions in the Common Shares of
the Company were  effected by  Opportunity  LP and  Opportunity  Ltd in ordinary
brokerage transactions.


                        Number of                              Purchase Price
        Date            Shares           Security Type         per Share ($)
        ----            ---------        -------------         --------------

        10/30/2007         5,000          Common Shares           0.4700
        10/31/2007        35,200          Common Shares           0.4359
        11/01/2007           100          Common Shares           0.4500
        11/02/2007        10,000          Common Shares           0.4550
        11/05/2007        55,559          Common Shares           0.4821
        11/07/2007        25,000          Common Shares           0.4700
        11/15/2007        16,000          Common Shares           0.4374
        11/15/2007         4,000          Common Shares           0.4375
        11/16/2007        20,000          Common Shares           0.4225
        11/19/2007        51,100          Common Shares           0.4340
        11/20/2007         6,000          Common Shares           0.4417
        11/23/2007        15,000          Common Shares           0.4167
        11/26/2007        35,000          Common Shares           0.4129
        11/30/2007        30,000          Common Shares           0.4500
        12/03/2007        35,100          Common Shares           0.4500
        12/05/2007        10,000          Common Shares           0.4540
        12/06/2007        30,000          Common Shares           0.4378


          Except  for  the  transactions  listed  above,  none  of  the  persons
referenced in Item 2 traded securities of the Company during the period starting
October 29, 2007 and ending December 6, 2007."



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

          No material change.


Item 7.   Material to be Filed as Exhibits.
          --------------------------------

          Not applicable.





                                   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.


April 7, 2008                         XMARK OPPORTUNITY PARTNERS, LLC
                                      By:  XMARK CAPITAL PARTNERS, LLC
                                           its Managing Member

                                      By:  /s/ Mitchell D. Kaye
                                           -------------------------------------
                                          Name:  Mitchell D. Kaye
                                          Title: Chief Executive Officer



  Attention: Intentional misstatements or omissions of fact constitute Federal
                   criminal violations (See 18 U.S.C. 1001).