UNITED STATES

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                  SCHEDULE 13D

                   Under the Securities Exchange Act of 1934

                                (Amendment No. 13)*



                          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)

                                March 24, 2008
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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:             15,494,504*
                                     -------------------------------------------
    Shares Beneficially            8. Shared Voting Power:
                                     -------------------------------------------
    Owned by
    Each Reporting                 9. Sole Dispositive Power:        14,494,504*
                                      ------------------------------------------
    Person With                    10. Shared Dispositive Power:
                                      ------------------------------------------
--------------------------------------------------------------------------------
11. Aggregate Amount Beneficially Owned by Each Reporting Person:   15,494,504*

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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):   45.4%*
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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 March 24, 2008,  Opportunity  LP held 3,027,648  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 March 24, 2008,  Opportunity Ltd held 6,413,174 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 March 24,  2008,  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. 13 to Schedule  13D.  As of March 24, 2008,  Goodnow held  3,529,951  Common
Shares of the Company in addition to the Common Shares of the Company referenced
above.  As of  March  24,  2008,  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
March 24, 2008,  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 15,494,504
Common  Shares of the  Company,  or 45.4% of the  Common  Shares of the  Company
deemed issued and outstanding as of March 24, 2008.










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 March 24, 2008,  Opportunity  LP held  3,027,648  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 March 24, 2008,  Opportunity  Ltd held 6,413,174  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 March 24,  2008,  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. 13 to Schedule  13D.  As of March 24,  2008,  Goodnow  held
3,529,951  Common  Shares of the Company in addition to the Common Shares of the
Company  referenced  above. As of March 24, 2008,  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 March 24, 2008, 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 15,494,504  Common Shares of
the  Company,  or 45.4% of the Common  Shares of the Company  deemed  issued and
outstanding as of March 24, 2008.

          During  the  sixty  (60)  days on or  prior  to March  24,  2008,  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 ($)
        ----            ---------        -------------         --------------

        1/23/2008            100          Common Shares           $0.3900
        1/28/2008          1,000          Common Shares           $0.3900
        1/29/2008         16,000          Common Shares           $0.3900
        1/30/2008          2,020          Common Shares           $0.3850
        1/31/2008            100          Common Shares           $0.3900
        2/01/2008         10,000          Common Shares           $0.3800
        2/04/2008          7,100          Common Shares           $0.3800
        2/05/2008         30,200          Common Shares           $0.3815
        2/14/2008         10,000          Common Shares           $0.3900
        2/19/2008          6,100          Common Shares           $0.3900
        2/22/2008          1,000          Common Shares           $0.3900
        2/26/2008          7,000          Common Shares           $0.3907
        2/28/2008          1,100          Common Shares           $0.3950
        3/04/2008          5,000          Common Shares           $0.3900
        3/06/2008         10,800          Common Shares           $0.3588
        3/12/2008          5,000          Common Shares           $0.3900
        3/12/2008         20,000          Common Shares           $0.3825
        3/19/2008         10,000          Common Shares           $0.3800
        3/20/2008         20,000          Common Shares           $0.3800
        3/24/2008         10,000          Common Shares           $0.3600

          Except  for  the  transactions  listed  above,  none  of  the  persons
referenced in Item 2 traded  securities of the Company during the sixty (60) day
period on or prior to March 24, 2008.






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).