OPTION AGREEMENT

         THIS OPTION AGREEMENT (this "Agreement") is made and executed this 28th
day of September, 1998, by and between JOLLY ACRES LIMITED PARTNERSHIP and
ARBITRAGE LAND LIMITED PARTNERSHIP ("Sellers") and CORPORATE OFFICE PROPERTIES,
L.P., its permitted successors and assigns ("Buyer").

                                    RECITALS
                                    --------

         Sellers are the owners of those various parcels of land identified and
described more specifically in Exhibit "A", attached hereto and by this
reference made a part hereof. Each of the Sellers, individually, as to those
parcels owned by each of them are willing to grant to Buyer an option to
purchase the parcels on the terms and conditions as set forth herein. Buyer is
willing to accept said option on the terms and conditions set forth herein and
for the considerations provided for hereafter.

         NOW THEREFORE, in consideration of the premises and other good and
valuable consideration, the adequacy of which is hereby acknowledged, Sellers
hereby grant to Buyer the exclusive right and option (irrevocable except upon
the express terms and conditions of this Agreement) during the term hereof to
purchase from Sellers, all of those parcels of land located in the National
Business Park in Anne Arundel County, State of Maryland and more fully described
in Exhibit "A" hereto (the "Property") upon the terms and subject to the
conditions hereinafter set forth. It is hereby irrevocably acknowledged,
confirmed and agreed by Sellers that the mutual obligations and covenants of the
parties hereunder and the entry by affiliates of Sellers and Buyer into other
agreements as of even date herewith, constitute adequate and appropriate
consideration for the option provisions of this Agreement.

         1.       Payment of Purchase Price.
                  -------------------------

                  (a) The Purchase Price for each of the separate parcels
comprising the Property shall be the higher of (i) the Fair Market Value of the
specific parcel (as determined pursuant to paragraph 1(b), or (ii) the Seller's
Book Value of the specific parcel (as determined pursuant to paragraph 1(c) as
of the date of a Buyer's Appraisal Process Notice (as defined below) relating to
that specific parcel, and shall be paid by Buyer to the Sellers as provided in
paragraph 3.

                  (b) If Buyer is at anytime considering exercising its option
to purchase any parcel within the Property, Buyer shall first give notice to
Sellers specifically noting the parcel or parcels under consideration (the
"Appraisal Process Notice") in order to begin the appraisal process under this
paragraph 1(b) and to determine the Purchase Price of the parcels within the
Property then being considered. Within ten (10) days after Buyer gives the
Appraisal Process Notice, Buyer and Sellers shall arrange to meet in person
through their appointed agents and shall use their best efforts for a period of
ten (10) days from the date of their first meeting ("Agreement Period") to agree
upon a Fair Market Value for the parcel or parcels then being considered within
the Property. If the parties can agree then such agreed upon sum shall be the





Fair Market Value of the parcels then being considered. If the parties cannot
agree then within ten (10) days of the end of the Agreement Period Buyer and
Sellers shall each retain an MAI Appraiser and obtain at their own cost and
expense (subject to paragraph (d) hereof) a certified appraisal with respect to
the value of the parcels within the Property being considered. Each appraiser
shall have forty-five (45) days after the last day of the Agreement Period to
determine the value of the parcel(s) and provide copies of their appraisals to
both Buyer and Sellers. The Fair Market Value shall be the average of these two
appraisals, provided that the higher valuation is not more than one hundred and
twenty percent (120%) of the lower valuation. In the event the valuations are
more than twenty percent (20%) apart, then the appraisers within five (5) days
after exchange of the appraisals shall jointly select a third MAI appraiser
whose valuation shall be substituted for the average of the two appraisals and
be the Fair Market Value, provided it falls between the two valuations selected
by the other appraisers. The third appraiser shall have thirty (30) days from
his or her selection to determine the value of the parcel(s) then under
consideration. If the third appraiser selects a valuation that does not fall
between the valuations determined by the other two appraisers, then the
valuation of the appraiser that is closest to the valuation selected by the
third appraiser shall be substituted for the average of the two appraisals as
provided above and shall be the Fair Market Value. The expense of the third
appraiser shall be divided equally between Buyer and Sellers (subject to
paragraph 1(d) hereof). All appraisers appointed under this Agreement shall be
independent MAI appraisers who have at least five (5) years experience in
appraising commercial real estate in Anne Arundel County, Maryland. Neither
party shall be precluded from appointing an independent appraiser whom such
party had previously employed as an independent appraiser, except that the third
appraiser, if appointed, may not have been previously employed by either party.

                  (c) Seller's Book Value is defined and shall be the net dollar
amount shown for any specific parcel within the Property as same appears as an
asset on the balance sheet of the particular Seller on any particular date.
Sellers shall maintain their books in accordance with generally accepted
accounting principals, consistently applied, and will provide to Buyer such
access to Seller's books and accounting records as shall be reasonably required
for a determination of Seller's Book Value to be made. Seller represents that
Seller's Book Value as of the date hereof for each parcel comprising the
Property is approximately as listed on Exhibit "A" attached hereto. Sellers
shall give Buyer written notice of Seller's Book Value for each parcel
comprising the Property as of January 1 and July 1 of each year during the
Option Period, and for each parcel specified in an Appraisal Process Notice as
of the date of the Appraisal Process Notice, such notice to be given within ten
(10) days after each of said dates.

                  (d) If Buyer gives the Appraisal Process Notice but does not
thereafter proceed to exercise the option to purchase the designated parcels
within the Property within thirty (30) days after the determination of the
Purchase Price of the portion of the Property being considered, then,
notwithstanding any contrary provisions of paragraph 1(b), all expenses incurred
by either party in retaining appraisers including the third appraiser if
required shall by paid by Buyer.


                                       2



         2.       Right to Inspect.
                  ----------------

                  (a) From and after execution of this Agreement by both Buyer
and Sellers, Buyer and Buyer's consultants shall have the right to enter upon
the Property and each parcel comprising same and conduct, at Buyer's sole
expense, any engineering tests, development and land use studies, environmental
analysis, soil tests, topographical and other surveys, wetlands and flood plain
delineations, and other surveys, tests and studies (collectively, "Site
Investigations") as Buyer deems necessary. Buyer shall give Sellers at least one
(1) day's notice of its desire to enter the Property to inspect and Buyer shall
coordinate the scheduling of such inspection with Seller, taking into account
any work Seller may be performing on the Property. All lands, trees, shrubs,
grass and field areas shall be restored as closely as possible to their pre-test
conditions. Buyer and its consultants shall enter and test the Property at their
own risk; and Buyer and/or its consultants shall carry adequate commercial
general liability insurance of not less than $1,000,000 combined single limit
naming Sellers as an additional insured. Buyer and/or its consultants shall
provide Sellers with a certificate evidencing such insurance promptly upon
request. Further, Buyer shall indemnify and save Sellers harmless from any and
all suits, claims of injuries and judgments, and reasonable attorney's fees, in
any way arising out or such entry and testing of the Property, which
indemnification and obligation to hold the Sellers harmless shall survive any
termination of this Agreement.

         3.       Exercise of Option and Settlement.
                  ---------------------------------

                  (a) Buyer may from time to time exercise its option to
purchase the Property or any parcel or parcels within same by sending to Sellers
a written notice of such exercise at any time after the date hereof and on or
before the expiration of the Option Period (as herein defined); provided,
however, that any such exercise(s) must occur, if at all, within thirty (30)
days after the date on which the Purchase Price of the subject parcel(s) is
determined pursuant to paragraph 1. The term of this Option shall commence on
the date hereof and automatically terminate and expire on that date which is
five (5) calendar years following the date hereof ("Option Period").

                  (b) Settlement and closing of title on the parcel or parcels
which are the subject of any Appraisal Process Notice ("Settlement") shall be
held at a location selected by the Buyer, and shall occur on the date which
shall be the first to occur of (i) ninety (90) days after the receipt by Sellers
of notice of the exercise of the Option as to any parcel or (ii) such earlier
date as Buyer, upon at least ten (10) days prior written notice to Sellers,
shall select, provided that, on such earlier date the Purchase Price for the
Property has been determined.

                  (c) At Settlement, the Buyer shall pay Sellers, in cash or by
certified, cashier's, treasurer or title company check, or by wire transfer, the
Purchase Price determined for each separate parcel.

                  (d) At Settlement, title to the portions of the Property being
sold shall be good and marketable, free of all liens, encumbrances,
encroachments and easements other than the Permitted Encumbrances (as
hereinafter defined), and possession of the portions of Property then


                                       3



being transferred shall be given to Buyer free of all tenancies or other rights
of use or occupancy. A deed containing covenants of special warranty and further
assurances shall be executed by Sellers (as appropriate between them), at
Buyer's expense, which shall convey fee simple title to the portions of the
Property being conveyed together with all improvements, rights, alleys, ways,
waters, privileges, easements, appurtenances, and advantages benefiting such
portions of the Property, and shall be delivered to Buyer at Settlement.

                  (e) Within thirty (30) days after receipt by Sellers of notice
of any exercise of the Option, the Buyer, at Buyer's expense, shall have the
title to the portion of the Property which is the subject of the exercise
examined by a reputable title insurance company and have such title insurance
company issue a title insurance commitment (the "Title Commitment") to assure
Buyer that, as of the examination date, title to the particular portion of the
Property is good and marketable and insurable at ordinary prevailing title
insurance rates and that any exceptions to title contained in the Title
Commitment are acceptable to Buyer. By the thirtieth (30th) day after receipt by
Sellers of notice of any exercise of the Option, Buyer shall provide to Sellers
a copy of the Title Commitment and either advise Sellers in writing that all
exceptions to title contained in the Title Commitment are acceptable to Buyer or
advise Sellers in writing of those exceptions to title contained in the Title
Commitment that are unacceptable to Buyer; provided, however, that Buyer shall
be required to accept all matters shown on the Subdivision Plats and any
amendments thereto pursuant to paragraph 7 hereof. Failure of Buyer to examine
title or to advise Sellers of the acceptability of title within the time periods
required hereunder shall be deemed an acceptance of all title matters. Within
fifteen (15) days after receipt of a notice from Buyer advising Sellers that
certain title exceptions are unacceptable to Buyer, Sellers shall notify Buyer
whether Sellers will cure any of the unacceptable title exceptions. Failure of
Sellers to provide notice within such time period shall be deemed an election by
Sellers not to cure the unacceptable title exceptions. If Buyer has timely
notified Sellers of unacceptable title matters then, unless Sellers have timely
elected to cure such title exceptions as provided hereunder, Buyer, by written
notice to Sellers, may, within fifteen (15) days after expiration of the time
period for Sellers to elect to cure, either waive such unacceptable title
exceptions (in which case such exceptions shall be deemed acceptable to Buyer)
or terminate the Option as to those portions of the Property which are then the
subject of an Appraisal Process Notice. Failure of Buyer to notify Sellers in
such fifteen (15) day period shall be deemed an election by Buyer to waive the
unacceptable title exceptions. If Sellers notify Buyer that Sellers will cure
any unacceptable title exception, then Sellers shall be obligated to promptly
and, in all events, prior to Settlement, proceed to cure such title exception in
such manner that the defect or objection to the title will not appear in the
Buyer's title insurance policy. All exceptions to title accepted by Buyer or
deemed to be accepted by Buyer under the provisions of this paragraph (other
than mortgages, deeds of trust and other liens [excluding liens for current
taxes and assessments to be adjusted under paragraph 3(f)], all of which shall
be discharged by Sellers at or prior to Settlement) shall constitute "Permitted
Encumbrances." Notwithstanding the foregoing, from and after the date hereof and
continuing until the expiration of the Option Period, except as otherwise
permitted hereunder, Sellers shall not change or permit to be changed title to
the Property or any portion thereof in a manner which would materially prevent
or interfere with the development of the separate parcels comprising the
Property. Nothing herein shall preclude Sellers from placing liens on the
Property in connection with financings or refinancings, it being


                                       4



understood that it is the obligation of Sellers to remove such liens with
respect to Property being purchased by Buyer hereunder at the time of
Settlement.

                  (f) All costs, including taxes, insurance and any and all
costs relating to the ownership of the Property and each portion of same shall
be borne by Sellers until time of any Settlement hereunder. All taxes, general
or special, and all other public, governmental or other assessments against each
parcel comprising the Property payable on an annual basis are to be adjusted and
apportioned as of the date of Settlement as to each parcel then being
transferred and are to be assumed and paid after Settlement by Buyer. The costs
of all recordation taxes and transfer taxes shall be split and paid equally by
Buyer and Sellers. All agricultural transfer tax or taxes, if any, shall be paid
by Sellers. All other closing costs incurred by Buyer, including, without
limitation, recording charges, document preparation charges, notary fees and
title insurance premiums shall be paid by Buyer. Sellers and Buyer shall each
pay their respective legal costs.

                  (g) At Settlement hereunder, the Sellers shall execute and
deliver to the Buyer an affidavit, in form sufficient to satisfy all Internal
Revenue Service requirements, stating that Sellers are not a "foreign person"
(as defined by the Foreign Investment in Real Property Tax Act and the
regulations promulgated thereunder) so that Buyer is not legally required to
withhold any portion of the Purchase Price then being paid at any Settlement
hereunder.

                  (h) At Settlement hereunder the Sellers shall execute and
deliver reasonable and customary title affidavits as required by Buyer's title
company.

         4.       Risk of Loss. The Property and each parcel comprising same
is to be held at the risk of the Sellers until legal title has passed.

         5.       Seller's Warranties and Representations. Sellers warrant,
represent and covenant to Buyer the following items which are true in all
material respect and shall be deemed to have been restated at the time of each
Settlement hereunder:

                  (a) As of the date hereof and as of each Settlement, Sellers
will be the owner of 100 percent fee simple interest in the Property and or the
portion of same then being sold, and will not have entered into any contract of
sale, option agreement, right of first refusal or other agreement for the sale
of any part of the Property then subject to the Option.

                  (b) The Sellers have full power and authority to execute,
deliver and perform this Agreement in accordance with its terms.

                  (c) To Sellers' knowledge, as of the date of this Agreement,
the Property is zoned to permit its use for office and warehouse purposes and
Sellers shall not join in or consent to any change in the zoning of the Property
which would prohibit its use for office and warehouse purposes.


                                       5



                  (d) To Sellers' knowledge, there are no underground storage
tanks on the Property.

                  (e) To their knowledge, Sellers have not used, generated,
stored or disposed, and from and after the date of this Agreement, except to the
extent consistent with current real estate industry practices for such type of
property, consistent with use of the Property for office and warehouse purposes,
and permitted under governmental regulations, will not use, generate, store or
dispose, on, under or about the Property any hazardous waste, toxic substance or
related materials or any friable asbestos or substance containing asbestos.

         The foregoing warranties shall terminate as to a specific parcel twelve
(12) months after Settlement hereunder as to each such parcel.

         6.       Right of First Refusal; Termination of Option As To Certain
 Parcels.

         Notwithstanding any other provision herein set forth it is agreed and
specifically understood by Buyer that at all times while this Option shall be in
effect Sellers shall be permitted to actively market the Property and each
parcel comprising same; and further that if Sellers receive a bona fide
third-party expression of intent to purchase the Property or any portion of same
or any partnership interest in Sellers which Sellers desire to accept, Sellers
shall first offer Buyer the opportunity to purchase the Property or portion of
same (the "Right of First Refusal") at the same price and upon the same terms
and conditions as are provided in the expression of intent in accordance with
the following procedure:

                  (a) Sellers shall cause the expression of intent to be reduced
to writing, which writing may take the form of a letter of understanding, term
sheet or other expression of interest which includes price and, in the opinion
of counsel for the Sellers, sufficient other terms and conditions to describe
the proposed transaction (the "Offer"). Sellers shall notify Buyer, in writing,
of its desire to accept the Offer (the "Initial Notice"). The Initial Notice
shall set forth the parcel or portion of the Property subject to the Offer and
such other material terms and conditions of the Offer as are reasonable for
Buyer to analyze the Offer, and shall be accompanied by a copy of the Offer.

                  (b) Buyer shall have the right, exercisable upon written
notice to Sellers within fifteen (15) days after Buyer's receipt of the Initial
Notice, to accept or reject the Offer contained in the Initial Notice. If by its
reply Buyer accepts the Offer of Sellers, such reply notice shall be accompanied
by the deposit specified in the Offer, if any, and shall constitute an agreement
binding on Sellers and Buyer to sell and purchase the particular portion of the
Property which is the subject of the Offer, at the price and upon the terms and
conditions stated in the Initial Notice.

                  (c) If Buyer does not unconditionally accept the Offer of
Sellers contained in the Initial Notice within such fifteen (15) day period or
does not respond to the Initial Notice within such fifteen (15) day period, time
being of the essence, then the Option herein granted to Buyer as to the portion
of the Property which is the subject of the Offer shall terminate and


                                       6



expire and Seller shall have the right to sell that portion of Property on the
terms and conditions specified in the Offer and free and clear of Buyer's rights
hereunder. If the contemplated sale is not completed by the date set forth in
the Offer, in accordance with the terms of the Offer, Buyer's purchase option
and Right of First Refusal for the pertinent portion of the Property shall be
reinstated and Owner shall again be required to comply with the terms of this
Agreement.

         Buyer and Sellers acknowledge and agree that (i) a Sellers' Development
(as defined below) in accordance with paragraph 8 shall not be subject to the
Right of First Refusal, but (ii) any intent to develop all or any portion of the
Property which is not a Sellers' Development shall be deemed an offer to
purchase (a "ROFR Development"), shall be subject to the Right of First Refusal,
and shall be presented to Buyer in accordance with subparagraph 6(a) above as an
Offer to participate in the development as Sellers' co-developer. If an Offer
for a ROFR Development is presented to Buyer, then notwithstanding anything to
the contrary set forth above, within fifteen (15) days after the Initial Notice,
Buyer shall be entitled either to exercise the Option pursuant to paragraph 3,
or to accept or reject (in accordance with subparagraph (b)) the Offer. If Buyer
accepts an Offer for a ROFR Development, then Buyer shall be deemed to have
waived any due diligence period, whether set forth in the Offer or in any
expression of intent by the third-party co-developer(s), during which Buyer
would otherwise be entitled to conduct inspection activities on the pertinent
portions of the Property.

         7.       Resubdivision. The Property currently consists of a number of
separate subdivided parcels as shown on certain Subdivision Plats recorded among
the Land Records of Anne Arundel County, Maryland. Nothing herein shall be
deemed to prohibit Sellers from modifying the lot lines and/or sizes of the
various parcels as long as such changes are processed diligently through the
governmental subdivision process and written notice of such proposed changes is
given to Buyer. In addition Sellers shall notify Buyer when any resubdivision
has occurred and provide Buyer with a copy of the revised final resubdivision
plat.

         8.       Termination of Option - Construction of Buildings.
                  -------------------------------------------------

                  (a) Notwithstanding any other provision herein set forth, but
subject to the terms and conditions set forth in this paragraph, it is agreed
between the parties that nothing herein shall be deemed to prohibit or restrict
Sellers' rights to proceed with the development and construction of buildings on
any or all of the parcels comprising the Property by Sellers alone, or together
with others so long as none of the agreements between Sellers and its
co-developers in existence on the Extinguishment Date (as defined below) provide
for the aggregate interest of any such other co-developers to exceed a fifty
percent (50%) equity interest in the Sellers' Development project when completed
(a "Sellers' Development"). To that end it is agreed that if at any time while
the Option herein granted shall be effective Sellers elect to proceed with
Sellers' Development of any parcel comprising the Property, Sellers shall give
written notice (a "Development Notice") to Buyer that they or either of them as
the case may be have elected to proceed with Sellers' Development. If any
co-developers are to participate in a Sellers' Development, the Development
Notice shall identify all such co-developers and Sellers shall certify, and
provide such information and pertinent documentation as shall be reasonably
required to demonstrate, that the equity interest test set forth above has been
satisfied. Upon


                                       7



receipt of a Development Notice which meets all of the foregoing requirements,
Buyer's rights to give an Appraisal Process Notice or exercise the Option with
respect to any parcel which is the subject of the Development Notice shall be
suspended until the earlier to occur of (i) the date of issuance of the building
permit for Sellers' Development or (ii) the date which is eighteen (18) months
after Buyer's receipt of a Development Notice (the "Suspension Period"). If
Sellers receive a building permit for Sellers' Development within the Suspension
Period, the Suspension Period shall be extended for a period of twelve (12)
months from the date of issuance of the building permit for Sellers' Development
(the "Extended Suspension Period"). During the Suspension Period and any
Extended Suspension Period, Sellers agree to proceed with Sellers' Development
with due diligence and in good faith. If a building permit for Sellers'
Development is not received during the Suspension Period, or if Sellers fail to
commence construction of Sellers' Development prior to the end of an Extended
Suspension Period, Buyer's rights under this Agreement shall revive. If Sellers
receive a building permit within the Suspension Period and commence construction
of Sellers' Development prior to the end of the Extended Suspension Period, then
with respect to any parcel which is the subject of that Sellers' Development,
Buyer's rights to give an Appraisal Process Notice, exercise the Option and all
other rights Buyer may have hereunder with respect to any parcel which is the
subject of the Sellers' Development shall terminate, expire and be extinguished
on the date such construction is commenced (the "Extinguishment Date").

                  (b) So long as Sellers comply with all of the provisions of
subparagraph 8(a), nothing herein shall preclude Sellers, either alone or with
co-developers, from entering into an agreement (a "Pre-Sell Agreement") at any
time to sell the parcel which is the subject of Sellers' Development, or the
building constructed on such parcel, to a third-party upon completion of
Sellers' Development, provided that any such Pre-Sell Agreement entered into
prior to the Extinguishment Date is conditioned on the Extinguishment Date
occurring. The purchaser under a Pre-Sell Agreement, as such, shall not be
considered a co-developer for purposes of the definition of a Sellers'
Development.

        9.       Miscellaneous.
                 -------------

                  (a) Sellers and Buyer warrant that, in connection with this
Agreement, they have dealt with no broker, agent or other party who may be
entitled to a commission or finder's fee, and each party agrees to indemnify the
other from any claims or damages, including reasonable attorneys' fees, that the
other may incur as a result of the violation of this warranty, which warranty
and indemnification shall survive settlement and any termination of this
Agreement.

                  (b) Any written notices required under the terms of this
Agreement shall be sent by Federal Express Delivery or other national overnight
delivery service and addressed as follows:


                                       8



                                    To Buyer:

                               Corporate Office Properties L.P.
                               401 City Avenue, Suite 615
                               Bala Cynwyd, PA 19004
                               Attention: Clay W. Hamlin, III

                                 with copies to:

                               F. Michael Wysocki, Esquire
                               Saul, Ewing, Remick & Saul LLP
                               Centre Square West
                               1500 Market Street - 38th Floor
                               Philadelphia, PA   19102

                                   To Sellers:

                               Jolly Acres Limited Partnership
                               Arbitrage Land Limited Partnership
                               c/o Constellation Properties, Inc.
                               250 West Pratt Street, 23rd Floor
                               Baltimore, MD  21201
                               Attention:  Secretary

Any party hereto may change its notice address by giving notice of such change
in accordance with this paragraph. Notice shall be deemed to have occurred upon
actual delivery.

                  (c) Time shall be the essence of this Agreement.

                  (d) If the last day of the Option Period or the date on which
Settlement is to occur, or the last day of any time period specified herein,
falls on a Saturday, Sunday or holiday, the period for the required action shall
be extended until 5:00 PM on the next business day.

                  (e) This Agreement contains the final and entire agreement
between the parties thereto, and neither party shall be bound by any terms,
condition, statement or representation not herein contained. The Agreement may
not be modified or changed orally, but only by agreement in writing, signed by
the party against whom enforcement of any such change is sought.

                  (f) The Agreement shall be governed by the laws of the State
of Maryland. The titles of the paragraphs are inserted as a matter of
convenience and for reference and in no way define, limit or describe the scope
of this Agreement or the intent of any provision hereof.


                                       9



                  (g) Upon any expiration or termination of this Agreement, the
Option to purchase the Property or any parcel thereof, or the Right of First
Refusal to the Property or any parcel thereof, each party hereto, or any other
party to whom the Buyer's rights have been collaterally assigned, shall promptly
execute such instruments in recordable form as any party hereto may reasonably
require to confirm such expiration or termination. This Agreement may be
recorded by either party hereto.

         10.      Successors and Assigns. This Agreement shall be binding upon
and inure to the benefit of the parties hereto and their respective successors
and assigns. Buyer shall have the right to assign this Agreement in whole or in
part without the consent of Sellers (i) to any entity controlled by,
controlling, or under common control with Buyer or Corporate Office Properties
Trust (where control shall mean owning directly or indirectly fifty percent
(50%) or more of the voting stock or voting interest of such entity), (ii) to
any person or entity designated by Buyer as purchaser of the Property or any
portion thereof (with respect to such portion only) after Buyer has exercised
the Option or the Right of First Refusal with respect thereto, but provided that
Buyer shall remain liable hereunder, or (iii) to any successor entity of Buyer
resulting from the acquisition of Buyer by such entity or a merger of Buyer
where such successor entity is the surviving entity. Buyer shall not have any
other right to assign this Agreement in whole or in part without the prior
written consent of Sellers, which consent shall not be unreasonably withheld or
delayed.


                                       10



         IN WITNESS WHEREOF, each of the parties hereto has executed or caused
this Agreement to be executed by its duly authorized representative on the day
and year first above written.

                                 JOLLY ACRES LIMITED PARTNERSHIP


                                 By:      Constellation Properties, Inc.,
                                          General Partner


                                 By:____________________________________
                                          Dan R. Skowronski, Secretary

                                 ARBITRAGE LAND LIMITED
                                 PARTNERSHIP

                                 By:      Constellation Properties, Inc.,
                                          General Partner


                                 By:____________________________________
                                          Dan R. Skowronski, Secretary


                                 CORPORATE OFFICE PROPERTIES, L.P.

                                 By:      Corporate Office Properties Trust,
                                                Its sole general partner


                                 By:____________________________________
                                          Clay W. Hamlin, III
                                          President and Chief Executive Officer


                                       11



                                   EXHIBIT "A"
                Description of Parcels Constituting the Property
                         Entities Which Own the Property
                               Current Book Values




Parcel                  Seller                                   Current Book Value
- ------                  ------                                   ------------------
                                                                 
                                                                    
Lot 1                   Jolly Acres Limited Partnership          $  1,882,652
Lot 3A                  Jolly Acres Limited Partnership          $  3,188,875
Lot 4-R                 Arbitrage Land Limited Partnership       $    368,816
Lot 5-R                 Arbitrage Land Limited Partnership       $    368,816
Lot 9                   Jolly Acres Limited Partnership          $  1,300,000
Lot 10                  Jolly Acres Limited Partnership          $  1,300,000
Lot 12                  Jolly Acres Limited Partnership          $  1,115,976
Lot 13                  Jolly Acres Limited Partnership          $  1,437,307
Lot 14                  Jolly Acres Limited Partnership          $  1,626,325
Lot 15                  Jolly Acres Limited Partnership          $  2,117,772
Lot 16                  Jolly Acres Limited Partnership          $  2,117,772
Lot 17                  Jolly Acres Limited Partnership          $    416,608
Lot 18                  Jolly Acres Limited Partnership          $  2,367,276
Lot 19                  Jolly Acres Limited Partnership          $  5,457,094
Lot 20                  Jolly Acres Limited Partnership          $  1,046,668
                                                                 
                                          Total:                 $ 26,111,958