Document:

Exhibit 4.1

 

104598 INCORPORATED UNDER THE CANADA BUSINESS CORPORATIONS
ACT CONSTITUÉE SOUS L’AUTORITÉ DE LA LOI CANADIENNE SUR LES SOCIÉTÉS PAR ACTIONS SEE REVERSE
FOR CERTAIN DEFINITIONS VOIR AU VERSO POUR CERTAINES DÉFINITIONS transferable on the books of the Company only upon surrender
of this certificate properly endorsed. This certificate is not valid unless countersigned by the Transfer Agent and Registrar of
the Company. IN WITNESS WHEREOF the Company has caused this certificate to be signed on its behalf by the facsimile signatures
of its duly authorized officers. C0000000230 | M **SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPE
CIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN
18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557
510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN1855751070
0000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN185575107000000
00Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Cle
mentia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementi
a*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pha
rmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmaceuticals*Inc.zero****SPECIMEN18557510700000000Clementia*Pharmace
SPECIMEN **018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****01855751070000000
0Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmace
uticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero***
*018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000
Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceu
ticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****
018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000C
lementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceut
icals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****0
18557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Clementia*Pharmaceuticals*Inc.zero****018557510700000000Cl
* * * 0 * * * 00000000 Number Numéro Shares Actions FULLY PAID AND NON-ASSESSABLE COMMON SHARES WITHOUT PAR VALUE IN THE
CAPITAL OF IS THE REGISTERED HOLDER OF EST LE PORTEUR INSCRIT DE THIS CERTIFIES THAT LES PRÉSENTES ATTESTENT QUE Dated:
COUNTERSIGNED AND REGISTERED CONTRESIGNÉ ET IMMATRICULÉ COMPUTERSHARE TRUST COMPANY, N.A. (CANTON, MA, JERSEY CITY,
NJ AND LOUISVILLE, KY) TRANSFER AGENT AND REGISTRAR AGENT DE TRANSFERT ET AGENT COMPTABLE DES REGISTRES COUNTERSIGNED AND REGISTERED
CONTRESIGNÉ ET IMMATRICULÉ COMPUTERSHARE INVESTOR SERVICES INC. SERVICES AUX INVESTISSEURS COMPUTERSHARE INC. (MONTREAL)
(TORONTO) TRANSFER AGENT AND REGISTRAR AGENT DE TRANSFERT ET AGENT COMPTABLE DES REGISTRES OR By / Par ______________________________
Authorized Officer - Représentant Autorisé By / Par ______________________________ Authorized Officer - Représentant
Autorisé President Présidente Secretary Secrétaire * * * * 0 * * * * * * * * * * * * * * 0 * * * * * * * *
* * * * * * 0 * * * * * * * * * * * * * * 0 * * * * * * * * * * * * * * 0 * * * * * CUSIP 185575107 ISIN US1855751079 Clementia
Pharmaceuticals Inc. transférables dans les registres de la Société seulement sur remise de ce certificat
endossé en bonne et due forme. Ce certificat n’est valide que s’il a été contresigné par
l’agent de transfert et agent comptable des registres de la Société. EN FOI DE QUOI la Société
a fait signer le présent certificat en son nom au moyen des facsimilés de signature de ses dirigeants dûment
autorisés. ACTIONS ORDINAIRES SANS VALEUR NOMINALE ENTIÈREMENT LIBÉRÉES DU CAPITAL-ACTIONS DE Jul 18,
2017 Le : 18 juil. 2017 Clementia Pharmaceuticals Inc. Clementia Pharmaceutiques Inc. The shares represented by this certificate
are transferable at the offices of Computershare Investor Services Inc. in Montreal, QC and Toronto, ON or at the offices of Computershare
Trust Company, N.A. in Canton, MA, Jersey City, NJ and Louisville, KY. Les actions représentées par ce certificat
peuvent être transférées aux bureaux de Services aux Investisseurs Computershare inc. à Montreal, QC
et Toronto, ON ou aux bureaux de Computershare Trust Company, N.A. à Canton, MA, Jersey City, NJ et à Louisville,
KY. CSAE_WIP_WWZQ_C01.mtl.pulls/000001/000001/i

    	 

    	

    

The shares represented by this certificate have rights, privileges,
restrictions and conditions attached thereto and the Company will furnish to a shareholder, on demand and without charge, a full
copy of the text of: (a) the rights, privileges, restrictions and conditions attached to each class authorized to be issued and
to each series in so far as the same have been fixed by the directors; and (b) the authority of the directors to fix the rights,
privileges, restrictions and conditions of subsequent series.

Les actions représentées par ce certificat sont
assorties de droits, privilèges, restrictions et conditions et la Société fournira à tout actionnaire,
sur demande et sans frais, une copie du texte intégral a) des droits, privilèges, restrictions et conditions rattachés
à chaque catégorie d’actions dont l’émission est autorisée et à chaque série, dans la mesure
fixée par les administrateurs; et b) de l’autorisation donnée aux administrateurs de fixer les droits, privilèges,
restrictions et conditions des séries ultérieures.

 

	The following abbreviations shall be construed
    as though the words set forth below opposite each abbreviation were written out in full where such abbreviation appears:	 	Les abréviations suivantes doivent
    être interprétées comme si les expressions correspondantes étaient écrites en toutes lettres
    :
	TEN COM	-  as tenants in common	 	TEN COM	-  à titre de
    propriétaires en commun
	TEN ENT	-  as tenants by the entireties	 	TEN ENT	-  à titre de tenants unitaires
	JT TEN	-  as joint tenants with rights of survivorship and not
    as tenants in common	 	JT TEN	-  à titre de copropriétaires
    avec gain de survie et non à titre de propriétaires en commun
	(Name) CUST (Name) UNIF GIFT MIN
    ACT (State)	-  (Name) as Custodian for (Name)
    under the (State) Uniform Gifts to Minors Act	 	(Nom) CUST
    (Nom) UNIF GIFT MIN ACT (État)	-  (Nom)
    à titre de dépositaire pour (Nom) en vertu de la Uniform Gifts to Minors Act de (État)
	 	 	 	 	 
	Additional abbreviations
    may also be used though not in the above list.	 	Des abréviations autres que celles
    qui sont données ci-dessus peuvent aussi être utilisées.

 

	For value received the undersigned hereby sells, assigns and
    transfers unto	 	Pour valeur reçue, le soussigné vend, cède
    et transfère par les présentes à

 

	 	 
	Insert name and address of transferee	Insérer le nom et l’adresse du cessionnaire
	 	 
	 	 

 

	shares represented by
    this certificate and does hereby irrevocably constitute and appoint	 	actions représentées
    par le présent certificat et nomme irrévocablement
	 	 	 
	 	 	 
	the attorney of the undersigned
    to transfer the said shares on the books of the Company with full power of substitution in the premises.	 	le fondé de pouvoir du soussigné
    chargé d’inscrire le transfert desdites actions aux registres de la Société, avec plein pouvoir
    de substitution à cet égard.

 

	LE :

    DATED:	 	 	 	 	 
	 	 	 	Signature of
    Shareholder / Signature de l’actionnaire	 	Signature of
    Guarantor / Signature du garant

 

	
        Signature Guarantee: The signature
        on this assignment must correspond with the name as written upon the face of the certificate(s), in every particular,
        without alteration or enlargement, or any change whatsoever and must be guaranteed by a major Canadian Schedule I chartered
        bank or a member of an acceptable Medallion Signature Guarantee Program (STAMP, SEMP, MSP). The Guarantor must affix a
        stamp bearing the actual words “Signature Guaranteed”.

         

        In the USA, signature guarantees must be done by members of a “Medallion
        Signature Guarantee Program” only.

         

        Signature guarantees are not accepted from Treasury Branches, Credit
        Unions or Caisses populaires unless they are members of the Stamp Medallion Program.
	 	Garantie de signature : La
                                                                                        signature         apposée aux fins de cette cession doit correspondre exactement au nom qui est inscrit au recto du
                                                                                        certificat, sans         aucun changement, et doit être garantie par une banque à charte canadienne de
                                                                                        l’Annexe 1 ou un membre         d’un programme de garantie de signature Medallion acceptable (STAMP, SEMP, MSP).
                                                                                        Le garant doit apposer un timbre         portant la mention « Signature garantie » ou « Signature
                                                                                        Guaranteed ».

         

        Aux États-Unis, seuls les membres d’un « Medallion
        Signature Guarantee Program » peuvent garantir une signature.

         

        Les garanties de signature ne peuvent pas être faites par des
        caisses d’épargne (« Treasury Branches »), des caisses de crédit (« Credit Unions »)
        ou des Caisses populaires, à moins qu’elles ne soient membres du programme de garantie de signature Medallion STAMP.

 

	 	 	 
	SECURITY INSTRUCTIONS - INSTRUCTIONS DE SÉCURITÉ	 	 
	 	 
	THIS IS WATERMARKED PAPER, DO NOT ACCEPT WITHOUT NOTING WATERMARK, HOLD TO LIGHT TO VERIFY WATERMARK.

                                                                                 

                                                                                PAPIER FILIGRANÉ, NE PAS ACCEPTER SANS VÉRIFIER LA PRÉSENCE DU FILIGRANE, POUR CE FAIRE, PLACER À LA LUMIÈRE.
	 
	 	 	 

BI_COMP_V2_03Exhibit 10.8

 

CLEMENTIA PHARMACEUTICALS
INC.

THIRD AMENDED AND RESTATED STOCK OPTION
PLAN

 

[_____], 2017

 

ARTICLE 1

PURPOSE

 

	1.1	Purpose

 

The purpose of this Third Amended and
Restated Stock Option Plan is to develop the interest and incentive of eligible employees, Directors, officers and Consultants
of Clementia Pharmaceuticals Inc. (the “Corporation”) or of its Affiliates, in the Corporation’s and
its Affiliates’ growth and development by giving eligible employees, Directors, officers and Consultants an opportunity
to purchase a total aggregate maximum amount of common shares of the capital of the Corporation (the “Common Shares”)
equal to 315,837 Common Shares (as such number may be adjusted pursuant to Article 5), providing incentives thereby advancing
the interests of the Corporation and its Affiliates, enhancing the value of the Common Shares for the benefit of all the shareholders
and increasing the ability of the Corporation and its Affiliates to attract, motivate and retain skilled and motivated individuals
in the service of the Corporation and its Affiliates.

 

ARTICLE 2 

INTERPRETATION

 

	2.1	Definitions

 

When used herein, unless the context or NI 45-106 otherwise
requires, the following terms have the following meanings, respectively:

 

	(a)	“Affiliate”
                                         has the meaning attributed to that term in NI 45-106;

 

	(b)	“As-Converted
                                         Basis” means the number of Shares that would be issued and outstanding should
                                         the Class A Preferred Shares and Class B Preferred Shares be converted into Common Shares
                                         of the Corporation in accordance with their terms;

 

	(c)	“Board”
                                         means the board of directors of the Corporation;

 

	(d)	“Business
                                         Day” means a day that is not a Saturday, Sunday or a statutory or legal holiday
                                         in the Province of Québec;

 

	(e)	“Cause” means with respect
                                to any Participant who is an employee or Consultant of the Corporation or of any of its Affiliates:
                                (i) any theft, fraud, dishonesty, or serious misconduct by such Participant involving the property,
                                business or affairs of the Corporation or any of its Affiliates or the carrying out of the Participant’s
                                duties as an employee or Consultant of the Corporation or of any of its Affiliates, (ii) any material
                                breach or non-observance by such Participant of any term of the employment or consulting agreement
                                with such Participant, including gross negligence and consistent

    	 

    	

    

failure or refusal to
perform his or her duties or responsibilities, after having been notified of such by the Corporation or its relevant Affiliate
and failed to remedy the situation within a reasonable delay, (iii) any conviction of such Participant to an indictable offense
by a court of competent jurisdiction, or (iv) any other action recognized as “just and sufficient cause” or “serious
reason” under applicable laws;

 

	(f)	“Class
                                         A Preferred Shares” means the Class A convertible preferred shares in the capital
                                         of the Corporation;

 

	(g)	“Class
                                         B Preferred Shares” means the Class B convertible preferred shares in the capital
                                         of the Corporation;

 

	(h)	“Committee”
                                         has the meaning attributed to that term in Section 3.2 hereof;

 

	(i)	“Common
                                         Shares” means the common shares in the capital of the Corporation;

 

	(j)	“Consultants”
                                         has the meaning attributed to that term in NI 45-106;

 

	(k)	“Convertible
                                         Securities” means any right, unit, option, warrant or any other security, including,
                                         without limitation, any loan, note or any other instrument or agreement evidencing indebtedness
                                         of the Corporation, which may be converted or exchanged into shares in the capital of
                                         the Corporation or which carries a right to acquire shares in the capital of the Corporation;

 

	(l)	“Date
                                         of Grant” means, for any Option, the date specified by the Board at the time
                                         it grants the Option or, if no such date is specified, the date upon which the Option
                                         was granted;

 

	(m)	“Director”
                                         means a member of the Board;

 

	(n)	“Disability”
                                         means the mental or physical state of a Participant such that:

 

		i)	the
                                         Board, other than the Participant, unanimously determine that the Participant has been
                                         unable, due to illness, disease, mental or physical disability, as confirmed by an independent
                                         medical evaluation conducted by a physician selected by the Board, to fulfill his obligations
                                         as an employee, Directors, officer or Consultant of the Corporation either for any consecutive
                                         six-month period or for any non-consecutives periods that, in the aggregate, total 12
                                         months in any consecutive 24-month period; or

 

		ii)	a
                                         court of competent jurisdiction has declared the Participant to be mentally incompetent
                                         or incapable of managing his affairs;

 

	(o)	“Exercise
                                         Notice” means a notice in writing, in the form set out in Schedule “B”
                                         hereto, signed by Participant and stating the Participant’s intention to exercise
                                         a particular Option;

    	 

    	

    

	(p)	“Exercise
                                         Price” means the price at which a Common Share may be purchased pursuant to
                                         the exercise of an Option;

 

	(q)	“Exercise
                                         Period” means the period of time during which an Option granted under this
                                         Plan may be exercised, provided however that the Exercise Period may not exceed ten (10) years from the relevant
Date of Grant;

 

	(r)	“Fully
                                         Diluted Basis” means the number of Common Shares outstanding at any time on
                                         an As-Converted Basis, including any stock dividends which have been declared but not
                                         issued and assuming all Convertible Securities have been converted or exchanged into
                                         Shares and all outstanding options, including those granted pursuant to this Plan, have
                                         been exercised;

 

	(s)	“Intellectual
                                Property Rights” means any and all of the following in any and all legal jurisdictions
                                around the world: (i) patents, patent applications, patent disclosures and all related
                                continuations, continuations-in-part, divisionals, reissues, re-examinations and renewals,
                                (ii) trademarks, service marks, trade dress, logos, trade names, service names, domain
                                names and corporate names, and registrations and applications for registration thereof,
                                (iii)  copyrights,  and  registrations  and  applications  for  registration  thereof, (iv) mask works, and registrations and
                                applications for registration thereof, (v) trade secrets and confidential business information, including without limitation,
                                know-how, manufacturing and product processes and techniques, biomaterials, research and development information, financial,
                                marketing and business data, pricing and cost information, technical data, business and marketing plans, and customer and
                                supplier lists and information, and (vi) other proprietary rights relating to any of the foregoing (including without
                                limitation associated goodwill and remedies against infringements thereof and rights of protection of an interest therein
                                under the laws of all jurisdictions); 

 

	(t)	“IPO”
                                         means an initial public offering of the Common Shares resulting in the Common Shares
                                         being listed on a major stock exchange in the United States, Canada, Europe or Asia;

 

	(u)	“Liquidity
                                         Event” means a merger or consolidation or other transaction in which greater
                                         than or equal to 50% of the voting power of shareholders of the Corporation is transferred
                                         to a third party or a sale, lease, license, transfer or other disposition of all or substantially
                                         all of the assets or Intellectual Property Rights of the Corporation (except to an Affiliate);

 

	(v)	“NI
                                         45-106” means National Instrument 45-106 – Prospectus and Registration
                                         Exemptions, as the same may be amended and/or replaced or supplanted from time to time;

 

	(w)	“Option”
                                         means a non-assignable, non-transferable right to purchase Common Shares under this Plan;

 

	(x)	“Participant”
                                         means a current full-time or part-time employee, a Consultant, a Director or an officer
                                         of the Corporation or of any of its Affiliates;

 

	(y)	“person”
                                         includes:

    	 

    	

    

		i)	an
                                         individual;

 

		ii)	a
                                         corporation;

 

		iii)	a
                                         partnership, trust, fund, syndicate, an association, organization, or other organized
                                         group of persons, whether incorporated or not; and

 

		iv)	an
                                         individual or other person in that person’s capacity as trustee, executor, administrator
                                         or personal or other legal representative;

 

	(z)	“Plan”
                                         means this Third Amended and Restated Stock Option Plan;

 

	(aa)	“Shareholders’ Agreement” means the third amended and restated
unanimous shareholders’ agreement of the Corporation dated as of March 16, 2017, as may be amended, restated or replaced
from time to time;

 

	(bb)	“Shares” means all shares of the Corporation issued and outstanding
at any particular time and includes the Common Shares, the Class A Preferred Shares, the Class B Preferred Shares, and any shares
or securities into which Shares may be converted or changed or that result from a consolidation, subdivision, reclassification
or redesignation of Shares, any shares or securities that are received as a stock dividend or distribution payable in shares or
securities of the Corporation, any shares received on the exercise of any option; warrant or other similar right and any shares
or securities that may be received by the parties hereto or bound hereby as a result of an amalgamation, merger, arrangement or
other reorganization of or including the Corporation;

 

	(cc)	“Stock Option Agreement” means a signed, written agreement between
Participant and the Corporation, in the form attached as Schedule “A” hereto, subject to any amendments or additions
thereto as may, in the discretion of the Board, be necessary or advisable, evidencing the terms and conditions on which an Option
has been granted under this Plan;

 

	(dd)	“Termination Date” means:

 

		i)	in the case of
                                                            a Participant whose employment, directorship or term of office with
                                                            the Corporation or any of its Affiliates is terminated for any reason
                                                            other than death, Disability or resignation, including a termination
                                                            with or without Cause, the earlier of: (a) the date that is the last
                                                            day of the minimum statutory notice period applicable to the Participant
                                                            pursuant to applicable employment standards legislation in the Province
                                                            of Québec or other foreign applicable laws, if any, and (b)
                                                            the date that is designated by the Corporation or any of its Affiliates,
                                                            as applicable, as the last day of the Participant’s employment or
                                                            term of office with the Corporation or any of its Affiliates, as applicable,
                                                            and “Termination Date” specifically does not mean
                                                            the date on which any period of reasonable notice that the Corporation
                                                            or any of its Affiliates, as applicable, may be required at law to
                                                            provide to the Participant (other than the minimum statutory notice
                                                            period as applicable), would expire;

    	 

    	

    

		ii)	in
                                         the case of a Participant whose employment, services, directorship or term of office
                                         with the Corporation or any of its Affiliates is terminated by reason of the death or
                                         Disability of the Participant, the date of death or Disability of such Participant;

 

		iii)	in
                                         the case of a Participant whose employment, services, directorship or term of office
                                         with the Corporation or any of its Affiliates is terminated by reason of the resignation
                                         of the Participant, the effective date of such resignation;

 

		iv)	in
                                         the case of a Participant who is a Consultant and whose consulting agreement or arrangement
                                         with the Corporation or any of its Affiliates terminates in the circumstances set out
                                         in subsection 4.8(d) hereof, the date that is designated by the Corporation or its relevant
                                         Affiliate as the date on which the Participant’s consulting agreement or arrangement
                                         is terminated, and “Termination Date” specifically does not mean the
                                         date on which any period of notice of termination that the Corporation or its relevant
                                         Affiliate may be required to provide to the Participant under the terms of the consulting
                                         agreement or arrangement, would expire; and

 

	(ee)	“Voting Trust Agreement” means any voting trust agreement of the
Corporation generally applicable to its shareholders who are otherwise Participants in force or to be put in place at any given
time and includes any power of attorney required to be provided pursuant thereto.

 

	2.2	Interpretation

 

	(a)	Whenever
                                         the Board or, where applicable, the Committee, is to exercise discretion in the administration
                                         of the terms and conditions of this Plan, the term “discretion” means the
                                         sole and absolute discretion of the Board or the Committee, as the case may be.

 

	(b)	As
                                         used herein, the terms “Article”, “Section”, “sub-section”
                                         and “paragraph” mean and refer to the specified Article, Section,
                                         sub-section and paragraph hereof, respectively.

 

	(c)	Words
                                         importing the singular include the plural and vice versa and words importing any gender
                                         include any other gender.

 

	(d)	In
                                         this Plan, a person (first person) is considered to control another person (second person)
                                         if the first person, directly or indirectly, has the power to direct the management and
                                         policies of the second person by virtue of:

 

		i)	ownership
                                         of or direction over voting securities in the second person;

 

		ii)	a
                                         written agreement or indenture;

 

		iii)	being
                                         the general partner or controlling the general partner of the second person; or

 

		iv)	being
                                         a trustee of the second person.

    	 

    	

    

	(e)	Unless
                                         otherwise specified, all references to money amounts are to Canadian currency.

 

ARTICLE
3
ADMINISTRATION

 

	3.1	Administration

 

Subject to Section 3.2 hereof
and the provisions of the Shareholders’ Agreement, this Plan will be administered by the Board and the Board has sole and
complete authority, in its discretion, to:

 

	(a)	determine
                                         the individuals (from among the Participants) to whom Options may be granted;

 

	(b)	grant
                                         Options in such amounts and, subject to the provisions of this Plan, on such terms and
                                         conditions as it determines including:

 

		i)	the
                                         time or times at which Options may be granted;

 

		ii)	the
                                         Exercise Price of any Option;

 

		iii)	the
                                         time or times when an Option becomes exercisable and, subject to Section 4.3 hereof,
                                         the duration of the Exercise Period of an Option;

 

		iv)	without
                                         limiting Section 4.10 hereof, whether restrictions or limitations are to be imposed on
                                         Common Shares that may be purchased pursuant to the exercise of any Option and the nature
                                         of such restrictions or limitations, if any; and

 

		v)	any
                                         acceleration of exercisability or waiver of termination regarding any Option, based on
                                         such factors as the Board may determine;

 

	(c)	interpret
                                         this Plan and adopt, amend and rescind administrative guidelines and other rules and
                                         regulations relating to this Plan; and

 

	(d)	make
                                         all other determinations and take all other actions necessary or advisable for the implementation
                                         and administration of this Plan.

 

The Board’s determinations
and actions within its authority under this Plan are conclusive and binding on the Corporation and all other persons. The day-to-day
administration of the Plan may be delegated to such officers and employees of the Corporation as the Board may in its sole discretion
determine.

 

	3.2	Delegation
                                         to Committee

 

To the extent permitted by
applicable law, the Board may, from time to time, delegate to a committee (the “Committee”) of the Board all
or any of the powers conferred on the Board under the Plan. In such event, the Committee will exercise the powers delegated to
it by the Board in the manner and on the terms authorized by the Board.  Any decision made or action

    	 

    	

    

taken by the Committee arising
out of or in connection with the administration or interpretation of this Plan in this context is final and conclusive.

 

	3.3	Total
                                         Common Shares Subject to Options

 

	(a)	The
                                         aggregate number of Common Shares that may be issued pursuant to the exercise of Options
                                         shall not exceed 315,837 Common Shares, subject to any adjustment pursuant to Article
                                         5.

 

	(b)	Notwithstanding
                                         the foregoing, in the event that the Common Shares become listed and posted for trading
                                         on a major stock exchange in the United States, Canada, Europe or Asia, unless otherwise
                                         approved by holders of a majority of the voting shares, the aggregate number of Common
                                         Shares which may be reserved for issuance under the Plan shall not exceed the maximum
                                         permitted by the rules and policies of such stock exchange.

 

	(c)	If
                                         an Option terminates for any reason prior to its exercise in full or is cancelled, the
                                         Common Shares issuable pursuant to such Option shall be added back to the number of Common
                                         Shares reserved for issuance under the Plan and such Common Shares will again become
                                         available for grant under this Plan.

 

	3.4	Eligibility

 

Subject to Section 4.8 hereof,
all Participants are eligible to participate in the Plan. Eligibility to participate does not confer upon any Participant any
right to be granted Options pursuant to the Plan. The extent to which any Participant is entitled to be granted Options pursuant
to the Plan will be determined in the sole and absolute discretion of the Board.

 

	3.5	Stock
                                         Option Agreements

 

All grants of Options under
Section 4.1 hereof shall be evidenced by Stock Option Agreements. Such Stock Option Agreements will be subject to the applicable
provisions of this Plan and will contain such further provisions as are required by this Plan and any other further provisions
that the Board may direct. Any one proper officer of the Corporation is authorized and empowered to execute and deliver, for and
on behalf of the Corporation, Stock Option Agreements to the Participants.

 

	3.6	Non-transferability

 

Except pursuant to Section
4.8, Options granted under this Plan may only be exercised during the lifetime of the Participant by such Participant personally.
No assignment or transfer of Options, whether voluntary, involuntary, by operation of law or otherwise, vests any interest or
right in such Options whatsoever in any assignee or transferee and immediately upon any assignment or transfer, or any attempt
to make the same, such Options will terminate and be of no further force or effect.

    	 

    	

    

ARTICLE 4 

GRANT OF
OPTIONS

 

	4.1	Grant
                                         of Options

 

The Board may, from time
to time, subject to the provisions of this Plan and such other terms and conditions as the Board may prescribe, grant Options
to any Participant.

 

	4.2	Exercise
                                         Price

 

Subject to the rules of
any stock exchange upon which the Common Shares may become listed, the Exercise Price of Common Shares under any Option shall
be as determined by the Board.

 

	4.3	Term
                                         of Options

 

Subject to the terms of the
Plan and unless an earlier termination date is specified by the Board and/or Stock Option Agreement, each Option expires on the
earlier of the following: (i) on the tenth (10th) anniversary of its Date of Grant
or (ii) the time immediately following the closing of a Liquidity Event.

 

	4.4	Vesting
                                         Period

 

Unless otherwise specified by
(i) the Board at the time of granting an Option, (ii) a Stock Option Agreement, or (iii) this Plan, 25% of each Option granted
will vest on the first anniversary of the Date of Grant, and an additional 1/36th will
vest at the end of each month thereafter, such that the entire Option will be vested following the fourth anniversary of the Date
of Grant.

 

	4.5	Exercise
                                         Period

 

	(a)	Only
                                         the Options which have vested pursuant to section 4.4 and which have not yet expired
                                         or terminated may be exercised by the Participant. Each Option or portion thereof which
                                         has vested and become exercisable may be exercised at any time (except if then expired
                                         or terminated), in whole or in part, for up to the total number of Common Shares with
                                         respect to which it is then exercisable. The Board may accelerate the date upon which
                                         any installment of any Option becomes exercisable.

 

	(b)	Subject
                                         to the provisions of this Plan and any Stock Option Agreement, Options may be exercised
                                         by means of a fully completed Exercise Notice delivered to the Corporation together with
                                         payment therefor.

 

	(c)	The
                                         Corporation shall give written notice of any proposed Liquidity Event to each Participant,
                                         together with a description of the effect of such Liquidity Event on outstanding Options,
                                         not less than ten (10) Business Days prior to the closing of the transaction resulting
                                         in the Liquidity Event.

    	 

    	

    

	4.6	Payment
                                         of Exercise Price

 

An Exercise Notice must be
accompanied by payment in full of the purchase price for the Common Shares to be purchased thereby. Such Exercise Price must be
fully paid in cash, or by certified cheque, bank draft or money order payable to the Corporation or by such other means as might
be specified from time to time by the Board. No Common Shares will be issued pursuant to the exercise of any Option until full
payment therefor has been received by the Corporation. Subject to Section 4.10 hereof, as soon as practicable after receipt of
any Exercise Notice and full payment, the Corporation will deliver to the Participant a certificate or certificates representing
the acquired Common Shares.

 

	4.7	Liquidity
                                         Event

 

Subject
to any provisions of any Stock Option Agreement:

 

	(a)	The Committee
                                         shall, without the consent of any Participant, take such steps as are necessary or desirable
                                         to cause the conversion or exchange of any outstanding Options into or for, rights or
                                         other securities of substantially equivalent value (or greater value), as determined
                                         by the Board in its discretion, in any entity participating in or resulting from a Liquidity
                                         Event (an “Alternative Award”); or

 

	(b)	If no
                                         Alternative Awards are available, the Committee shall, without the consent of any Participant,
                                         provide that, immediately prior to the consummation of the transaction constituting the
                                         Liquidity Event, vest all unvested Options; and

 

	(c)	Unless
                                         otherwise determined by the Committee at or after the time of grant, any Participant
                                         whose service is terminated by his or her employer for any reason other than for Cause
                                         within twelve (12) months following the consummation of a Liquidity Event, then with
                                         respect to all Options granted to the Participant prior to the date of the consummation
                                         of the Liquidity Event which were still outstanding at the time of such termination of
                                         service, all such unvested Options shall vest and to the extent exercisable shall remain
                                         exercisable until the earlier of the one-year anniversary of such termination of service
                                         or until the Option’s normal expiration date.

 

	4.8	Termination

 

Subject to the provisions of any Stock Option Agreement:

 

	(a)	If,
                                         at any time, a Participant ceases to be an employee of the Corporation or of any of its
                                         Affiliates as a result of any of the following: (i) the Participant’s death, (ii)
                                         the Participant’s Disability, or (iii) the Participant’s termination for
                                         any reason whatsoever other than for Cause, the Options granted to such Participant and
                                         vested as of the Termination Date shall remain exercisable by such Participant (or the
                                         Participant’s legal representative) until the earlier of: (i) 90 days following
                                         the Termination Date, and (ii) the expiration of such vested Options in accordance with
                                         their terms. In addition, as of the Termination Date, all unvested Options of such Participant
                                         shall expire and be of no further force or effect whatsoever and such Participant shall
                                         no longer be eligible for a grant of Options.

 

	(b)	If,
                                         at any time, a Participant ceases to be an employee of the Corporation or of any of its
                                         Affiliates as a result of the termination for Cause, then, as of the Termination Date,
                                         all

    	 

    	

    

vested and unvested Options
granted to such Participant shall expire and be of no further force or effect whatsoever and such Participant shall no longer
be eligible for a grant of Options.

 

	(c)	Where,
                                         in the case of a Consultant, the Participant’s consulting agreement or arrangement
                                         terminates by reason of: (i) the Participant’s death, (ii) the Participant’s
                                         Disability, or (iii) the Participant’s
termination by the Corporation or its relevant Affiliate for any reason whatsoever other than for breach of the consulting agreement
or arrangement (whether or not such termination is effected in compliance with any termination provisions contained in the Participant’s
consulting agreement or arrangement), or (iv) voluntary termination by the Participant, then any Options granted to such Participant
and vested as of the Termination Date, or as of the date of the death or Disability of the Participant, as the case may be, shall
remain exercisable by such Participant until the earlier of: (i) 30 days following the Termination Date, or the date of the death
or Disability of the Participant, as the case may be; and (ii) the expiration of such vested Options in accordance with their
terms. In addition, as of the Termination Date, all unvested Options of such Participant shall expire and be of no further force
or effect whatsoever and such Participant shall no longer be eligible for a grant of Options.

 

	(d)	Where,
                                         in the case of a Consultant, the Participant’s consulting agreement or arrangement
                                         is terminated by the Corporation or its relevant Affiliate for breach of the consulting
                                         agreement or arrangement or for Cause (whether or not such termination is effected in
                                         compliance with any termination provisions contained in the Participant’s consulting
                                         agreement or arrangement), then all vested and unvested Options granted to such Participant
                                         shall expire and be of no further force or effect whatsoever and such Participant shall
                                         no longer be eligible for a grant of Options.

 

	(e)	If,
                                         at any time, a Participant ceases to be a Director or officer of the Corporation or any
                                         of its Affiliates (and is not and does not continue as a Consultant or full-time employee
                                         of the Corporation or of any of its Affiliates), the Options granted to such Participant
                                         and vested as of the Termination Date may be exercised by such Participant pursuant to
                                         the same terms and conditions as those mentioned in subsections 4.8(c) and 4.8(d) above
                                         as if such Director or officer was a Consultant.

 

	(f)	Notwithstanding
                                         any other provisions of this Section 4.8, the Board may extend the expiration date of
                                         vested and unvested Options of a Participant who ceases to be an employee, Consultant,
                                         officer or Director of the Corporation or of any of its Affiliates beyond the expiry
                                         dates set out above, provided that such extended dates are not later than the assigned
                                         expiry date of any such Option.

 

	(g)	Unless
                                         the Board otherwise determines, Options are not effected by a change of employment or
                                         consulting arrangements within or among the Corporation its relevant Affiliate for so
                                         long as the employee or the Consultant continues to be an employee or a Consultant of
                                         the Corporation or of any of its Affiliates.

 

	4.9	Discretion
                                         to Permit Exercise

 

Notwithstanding the provisions
of Section 4.8 hereof, the Board may, in its discretion, at any time prior to or following the events contemplated in such section,
permit the exercise of any or all Options held by a Participant in the manner and on the terms authorized by the Board, provided
that the Board shall not, in any case, authorize the exercise of an Option pursuant to this Section 4.9 beyond the initial expiration
of the Exercise Period of the particular Option

    	 

    	

    

under the terms of the grant
of such Option.

 

	4.10	Ancillary
                                         Agreements

 

Each Participant
shall, at the time of exercising an Option, execute and deiiver to the Corporation(a) a counterpart and acknowledgement to
the Shareholders’ Agreement or any other shareholders’ agreement, in force at such date (if such Participant is
not already a party thereto) and (b) if requested by the Corporation, a Voting Trust Agreement (collectively, the
“Ancillary Agreements”). Each Participant acknowledges that the Ancillary Agreements restrict transfers of
Common Shares and may provide that any original share certificates of the Corporation shall be held by the Corporation or its
legal counsel.

 

	4.11	Conditions
                                         of Exercise

 

Each Participant shall,
when requested by the Corporation, sign and deliver all such documents relating to the granting or exercise of Options which the
Corporation or the Board deems necessary or desirable.

 

ARTICLE 5
SHARE CAPITAL ADJUSTMENTS

 

	5.1	General

 

The existence of any Options
shall not affect in any way the right or power of the Corporation or its shareholders to make, authorize or determine any adjustment,
recapitalization, reorganization or any other change in the Corporation’s capital structure or its business, or any amalgamation,

    	 

    	

    

combination, merger or
consolidation involving the Corporation, to create or issue any bonds, debentures, Common Shares or other securities of the Corporation
or to determine the rights and conditions attaching thereto, to effect the dissolution or liquidation of the Corporation or any
sale or transfer of all or any part of its assets or business, or to effect any other corporate act or proceeding, whether of
a similar character or otherwise, whether or not any such action referred to in this Section 5.1 would have an adverse effect
on this Plan or any Option granted hereunder.

 

	5.2	Reorganization of Corporation’s
                                         Capital

 

Should the Corporation
effect a subdivision or consolidation of Common Shares or any similar capital reorganization or a payment of a stock dividend
(other than a stock dividend that is in lieu of a cash dividend), or should any other change be made in the capitalization of
the Corporation that, in the opinion of the Board, would warrant an adjustment to the number of Common Shares referred to in Section
3.3(a), or the replacement of any existing Options in order to adjust (a) the number of Common Shares that may be acquired on
the exercise of any outstanding Options and/or (b) the Exercise Price of any outstanding Options in order to preserve proportionately
the rights and obligations of the Participants, the Board shall authorize such steps to be taken as may be equitable and appropriate
thereto.

 

	5.3	Other Events Affecting the Corporation

 

In the event of an amalgamation,
combination, merger or other reorganization involving the Corporation by exchange of Common Shares, by sale or lease of assets
or otherwise, that, in the opinion of the Board, warrants an adjustment to the number of Common Shares referred to in Section
3.3(a), or the replacement of any existing Options in order to adjust (a) the number of Common Shares that may be acquired on
the exercise of any outstanding Options or (b) the Exercise Price of any outstanding Options in order to preserve proportionately
the rights and obligations of the Participants, the Board shall authorize such steps to be taken as may be equitable and appropriate
thereto.

 

	5.4	Immediate Exercise of Options

 

Where the Board determines
that the steps provided in Sections 5.2 and 5.3 hereof would not preserve proportionately the rights and obligations of the Participants
in the circumstances or otherwise determines that it is appropriate, the Board may permit the immediate exercise of any outstanding
Options that are not otherwise exercisable.

 

	5.5	Issue by Corporation of Additional
                                         Shares

 

Except as expressly provided
in this Article 5, neither the issue by the Corporation of shares of any class or securities convertible into or exchangeable
for shares of any class, nor any conversion or exchange of such shares or securities, shall affect, and no adjustment by reason
thereof shall be made with respect to (a) the number of Common Shares that may be acquired on the exercise of any outstanding
Options or (b) the Exercise Price of any outstanding Options.

    	 

    	

    

	5.6	Fractions

 

No fractional Common Shares
will be issued on the exercise of an Option. Accordingly, if, as a result of any adjustment under Sections 5.2 to 5.4 hereof inclusive,
a Participant would become entitled to a fractional Common Share, such Participant shall have the right to acquire only the adjusted
number of full Common Shares and no payment or other adjustment will be made with respect to the fractional Common Shares so disregarded.

 

	5.7	Conditions of Exercise

 

The Plan and each Option
are subject to the requirement that if at any time the Board determines that the listing, registration or qualification of the
Common Shares subject to such Option upon any stock exchange or under any provincial, state or federal law, or that the consent
or approval of any governmental body, stock exchange or of the holders of the Common Shares generally, is necessary or desirable,
as a condition of, or in connection with, the granting of such Option or the issue or purchase of Common Shares thereunder, no
such Option may be granted or exercised in whole or in part unless such listing, registration, qualification, consent or approval
has been effected or obtained free of any conditions not acceptable to the Board. The Participant shall, to the extent applicable,
cooperate with the Corporation in relation to such registration, qualification or other approval and shall have no claim or cause
of action against the Corporation or any of its officers or directors as a result of any failure by the Corporation to obtain
or to take any steps to obtain any such registration, qualification or approval.

 

ARTICLE
6
MISCELLANEOUS PROVISIONS

 

	6.1	Legal
                                         Requirement

 

The Corporation is not obligated
to grant any Options, issue any Common Shares or other securities, make any payments or take any other action if, in the opinion
of the Board, in its sole discretion, such action would constitute a violation by a Participant or the Corporation of any provision
of any applicable statutory or regulatory enactment of any government or government agency.

 

	6.2	Withholding
                                         Taxes

 

The exercise of each Option
granted under this Plan is subject to the condition that if at any time the Corporation determines, in its discretion, that the
satisfaction of withholding tax or other withholding liabilities is necessary or desirable in respect of such exercise, such exercise
shall not be effective unless such withholding has been effected to the satisfaction of the Corporation. In such circumstances,
the Corporation may require that a Participant pay to the Corporation, in addition to and in the same manner as the Exercise Price
for the Common Shares, such amount as the Corporation is obliged to remit to the relevant taxing authority in respect of the exercise
of any such Option. Any such additional payment is due no later than the date of exercise of the relevant Options.

    	 

    	

    

	6.3	Rights
                                         of Participant

 

No Participant shall have
any claim or right to be granted an Option (including, without limitation, an Option granted in substitution for any Option that
has expired pursuant to the terms of this Plan), and the granting of any Option is not to be construed as giving any Participant
a right to remain in the employ of the Corporation. No Participant shall have any rights as a shareholder of the Corporation in
respect of Common Shares issuable on the exercise of rights to acquire Common Shares under any Option until the allotment and
issuance to the Participant of certificates representing such Common Shares.

 

	6.4	Compliance
                                         with Stock Exchange

 

The Board may make changes
to the terms of any granted Options or the Plan to the extent necessary or desirable to comply with any rules, regulations or
policies of any stock exchange on which the Common Shares may be listed following an IPO, provided that the value of previously
granted Options and the rights of Participants are not materially adversely affected by any such changes.

 

	6.5	Termination;
                                         Amendment

 

	(a)	The
                                         Plan will terminate and, for greater certainty, all unexercised Options shall terminate
                                         and expire on the earliest of: (i) the date upon which no further Common Shares remain
                                         available for issuance pursuant to Options which may be granted under the Plan and no
                                         Options remain outstanding; or (ii) immediately following closing of a Liquidity Event,
                                         unless renewed for such further period or otherwise determined by the Board in accordance
                                         with Article 4, and upon such terms and conditions as the Board may determine.

 

	(b)	Subject
                                         to the provisions of the Shareholders’ Agreement, the Board may, without notice,
                                         at any time or from time to time, amend, suspend or terminate this Plan or any provisions
                                         hereof in such respects as it, in its sole discretion, determines appropriate. No such
                                         amendment, suspension or termination of this Plan, without the consent of any Participant
                                         or the representatives of such Participant’s estate, as applicable, shall alter
                                         or impair any rights or obligations arising from any Option previously granted to any
                                         Participant under this Plan.

 

	6.6	Authorization
                                         of Sub Plans

 

Subject to the provisions
of the Shareholders’ Agreement, the Board may from time to time establish one or more sub-plans under the Plan for purposes
of satisfying applicable blue sky, securities or tax laws of various jurisdictions. The Board shall establish such sub-plans by
adopting supplements to this Plan containing (a) such limitations on the Board’s discretion under the Plan as the Board
deems necessary or desirable or (b) such additional terms and conditions not otherwise inconsistent with the Plan as the Board
shall deem necessary or desirable. All supplements adopted by the Board, subject to the provisions of the Shareholders’
Agreement, shall be deemed to be part of the Plan, but each supplement shall apply only to Participants within the affected jurisdiction
and the Corporation shall not be required to provide copies of any supplement to Participants in any jurisdiction which is not
the subject of such supplement.

    	 

    	

    

	6.7	Participation
                                         in the Plan

 

The participation of any
Participant in the Plan is entirely voluntary and not obligatory and shall not be interpreted as conferring upon such Participant
any rights or privileges other than those rights and privileges expressly provided in the Plan. In particular, participation in
the Plan does not constitute a condition of employment nor a commitment on the part of the Corporation to ensure the continued
employment of such Participant. The Plan does not provide any guarantee against any loss which may result from fluctuations in
the market value of the Common Shares. The Corporation does not assume responsibility for the income or other tax consequences
for the Participants and they are advised to consult with their own tax advisors.

 

	6.8	Effective
                                         Date

 

This Plan becomes effective
on the date hereof.

 

	6.9	Governing
                                         Law

 

The Plan, and determinations
made and actions taken in connection with the Plan, shall be governed by the laws of the Province of Québec and the federal
laws of Canada and construed in accordance therewith.

 

	6.10	Language

 

The Board confirms that
it is its wish that the Plan, as well as other documents relating thereto, be drawn up in English only. Le conseil d’administration
confirme sa volonté que ce Plan, de même que tous les documents s’y rattachant, soient rédigés
en anglais seulement.

 

[signature
page follows]

    	 

    	

    

The
undersigned executes this Third Amended and Restated
Employee Stock Option Plan as of the date first written
above.

 

	 	CLEMENTIA PHARMACEUTICALS INC.	 
	 	 	 	 
	 	 	 	 
	 	 	 	 
	 	 	 	 
	 	Per: 	                                   	 
	 	Name: Dr. Clarissa Desjardins 	 
	 	Title: President 	 

    	 

    	

    

SCHEDULE
“A”

 

STOCK OPTION AGREEMENT

 

Clementia Pharmaceuticals Inc. (the
“Corporation”) hereby grants to the Participant named below (the “Participant”), an
option (the “Option”) to purchase, in accordance with and subject to the terms, conditions and
restrictions of this Agreement, together with the provisions of the Third  Amended and Restated Stock Option Plan (the
“Plan”) of the Corporation dated [_____], 2017, the number of common shares in the capital of the
Corporation (“Common Shares”) at the price per share set forth below:

 

	 	Name of Participant: Date of Grant:	 	 	 
	 	Number of Common Shares:	 	 	 
	 	Exercise Price:	 	 	 
	 	Exercise Period:	 	 	 
	 	Vesting Period:	 	 	 

 

	1.	The
                                         terms and conditions of the Plan are hereby incorporated by reference as terms and conditions
                                         of this Stock Option Agreement and all capitalized terms used herein, unless expressly
                                         defined in a different manner, have the meanings ascribed thereto in the Plan.

 

	2.	Subject
                                         to Sections 4.7, 4.8 and 5.4 of the Plan, unless otherwise provided herein, each Option
                                         is exercisable in the portions set forth in Section 4.4 of the Plan.

 

	3.	In
                                         no event is the Option granted hereunder exercisable after the expiration of the relevant
                                         Exercise Period.

 

	4.	Nothing
                                         in the Plan or in this Stock Option Agreement will affect the Corporation’s or
                                         its relevant Affiliate’s right, to terminate the employment of, or term of
office of, or consulting agreement or arrangement with a Participant at any time for any reason whatsoever. Upon such
termination, a Participant’s rights to exercise Options will be subject to restrictions and time limits for the
exercise of Options. Complete details of such restrictions are set out in the Plan, and in particular in Section 4.8 of the
Plan.

 

	5.	Each
                                         notice relating to the Option, including the exercise thereof, must be in writing. All
                                         notices to the Corporation must be delivered personally or by prepaid registered mail
                                         and must be addressed to the President of the Corporation. All notices to the Participant
                                         will be addressed to the principal address of the Participant on file with the Corporation.
                                         Either the Corporation or the Participant may designate a different address by written
                                         notice to the other. Such notices are deemed to be received, if delivered personally,
                                         on the date of delivery, and if sent by prepaid, registered mail, on the fifth Business
                                         Day following the date of mailing.

 

	6.	When
                                         the issuance of Common Shares on the exercise of the Option may, in the opinion of the
                                         Corporation, conflict or be inconsistent with any applicable law or regulation of any
                                         governmental agency having jurisdiction, the Corporation reserves the right to refuse
                                         to issue such Common Shares for so long as such conflict or inconsistency remains outstanding.

    	 

    	

    

	7.	Except
                                         as specifically permitted by the Plan, the Option granted pursuant to this Stock Option
                                         Agreement may only be exercised during the lifetime of the Participant by the Participant
                                         personally and no assignment or transfer of the Option, whether voluntary, involuntary,
                                         by operation of law or otherwise, vests any interest or right in such Option whatsoever
                                         in any assignee or transferee, and immediately upon any assignment or transfer or any
                                         attempt to make such assignment or transfer, the Option granted hereunder terminates
                                         and is of no further force or effect. Complete details of this restriction are set out
                                         in the Plan.

 

	8.	The
                                         Participant hereby agrees that:

 

		a)	any
                                         rule, regulation or determination, including the interpretation by the Board of the Plan,
                                         the Option granted hereunder and the exercise thereof, is final and conclusive for all
                                         purposes and binding on all persons including the Corporation and the Participant; and

 

		b)	the
                                         grant of the Option does not affect in any way the right of the Corporation or its relevant
                                         Affiliate to terminate the employment of the Participant.

 

	9.	The
                                         Participant acknowledges and agrees that

 

		a)	as
                                         a condition of exercise of any Options, the Participant must agree to become a party
                                         to and be bound by any shareholders’ agreement and voting trust agreement then
                                         in effect, or otherwise required, applicable to the Participant who acquires Common Shares
                                         through the exercise of Options;

 

		b)	the                                          current version of such shareholders’
                                                            agreement, among other  things: (i) severely restricts any transfer of Common Shares; (ii) provides the Corporation and
                                                            certain shareholders the right to purchase Common Shares at a price which may, in certain circumstances, be less than the
                                                            exercise price paid by the Participant to acquire its Common Shares; (iii) may force the sale of the Common Shares underlying
                                                            Options, including in connection with certain Liquidity Events, and (iv) may grant power of attorney for the voting rights
                                                            attached to the Common Shares; and 

 

		c)	the
                                         voting trust agreement may among other things: (i) provide that the Common Shares acquired
                                         upon exercise of the Option may only be voted by a third party (and not the Participant);
                                         or (ii) grant power of attorney for the voting rights attached to the Shares.

 

Accordingly, if at any time
the Participant wishes to exercise any Options, the Participant should request from the Corporation a copy of the shareholders’
agreement and voting trust agreement then in effect, or otherwise required, and applicable to the Participant who acquires Common
Shares through the exercise of Options and carefully review it prior to completing any exercise of Options.

    	A2

    	

    

	10.	This
                                         Stock Option Agreement has been made in and is to be construed under and in accordance
                                         with the laws of the Province of Québec and the laws of Canada applicable therein.

 

	11.	The
                                         Participant confirms that it is its wish that the Plan, as well as other documents relating
                                         thereto (including this Stock Option Agreement), be drawn up in English only.  Le
                                         participant confirme sa volonté que ce Plan, de même que tous les documents
                                         s’y rattachant (incluant cette entente d’options), soient rédigés
                                         en anglais seulement.

 

	 	CLEMENTIA PHARMACEUTICALS INC.	 
	 	 	 	 
	 	By:  	 	 
	 	 	Name:	 
	 	 	Title:	 

 

I have read the foregoing
Stock Option Agreement and hereby accept the Option to purchase Common Shares in accordance with and subject to the terms and
conditions of such Stock Option Agreement and the Plan. I understand that I may review the complete text of the Plan by contacting
the President of the Corporation. I agree to be bound by the terms and conditions of the Plan governing the award.

 

	Date Accepted	 	Participant’s Signature	 
	 	 	 	 
	 	 	Participant’s Name

    (Please Print)	 

    	A3

    	

    

SCHEDULE “B”

 

STOCK OPTION PLAN EXERCISE
NOTICE FORM - OPTIONS

 

I,________________________________________________________________________________(print
name), hereby exercise the option to purchase_________________________________________Common Shares of Clementia
Pharmaceuticals Inc. (the “Corporation”) at a purchase price of $__________________________________ per
Common Share. This Exercise Notice is delivered in respect of the option to purchase ________________________ Common Shares
of the Corporation that was granted to me on __________________________________ pursuant to the Stock Option Agreement
entered into between the Corporation and me. In connection with the foregoing, I enclose cash, a certified cheque, bank draft
or money order payable to the Corporation in the amount of
$_______________as          full
payment for the Common Shares to be received upon exercise of the Option and all applicable withholding taxes.

 

	Date	 	Participant’s Signature

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