Exhibit 4.1

016570 003590127CRESTRICTED4057-423

COMMON STOCK

PAR VALUE $.001

COMMON STOCK

THIS CERTIFICATE IS TRANSFERABLE IN CANTON, MA AND JERSEY CITY, NJ

PSivida

Certificate Number

ZQ 000000

Shares

**600620******

***600620*****

****600620****

*****600620***

*****600620**

PSIVIDA CORP.

INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE

THIS CERTIFIES THAT

MR. SAMPLE & MRS. SAMPLE & MR. SAMPLE & MRS. SAMPLE

CUSIP 74440J 10 1

SEE REVERSE FOR CERTAIN DEFINITIONS

is the owner of

SIX HUNDRED THOUSAND SIX HUNDRED AND TWENTY

FULLY-PAID AND NON-ASSESSABLE SHARES OF THE COMMON STOCK OF

pSivida Corp. (hereinafter called the “Company”), transferable on the books of the Company in person or by duly authorized attorney, upon surrender of this Certificate properly endorsed. This Certificate and the shares represented hereby, are issued under, and shall be held subject to all of the provisions of, the Certificate of Incorporation, as amended, and the By-Laws of the Company (copies of which are on file with the Company and with the Transfer Agent), to all of which each holder, by acceptance hereof, assents. This Certificate is not valid unless countersigned and registered by the Transfer Agent and Registrar.

Witness the facsimile seal of the Company and the facsimile signatures of its duly authorized officers.

[signature appears here]

VP, Finance & CFO

[signature appears here]

Vice President, Corporate Affairs, General Counsel & Corporate Secretary

[signature appears here]

Managing Director

PSIVIDA CORP.

SEAL

DELAWARE 2008

DATED «Month Day, Year»

COUNTERSIGNED AND REGISTERED: COMPUTERSHARE TRUST COMPANY, N.A. TRANSFER AGENT AND REGISTRAR

By

AUTHORIZED SIGNATURE

SECURITY INSTRUCTIONS ON REVERSE

PSvida

PO BOX 43004, Providence, Rl 02940-3004

MR A SAMPLE

DESIGNATION (IF ANY)

ADD1

ADD 2

ADD 3

ADD 4

CUSIP XXXXXXXXX

Holder ID XXXXXXXXXX

Insurance Value 1,000,000.00

Number of Shares 123456

DTC 12345678 123456789012345

Certificate Numbers Num/No. Denom. Total

1234567890/1234567890 1 1 1

1234567890/1234567890 2 2 2

1234567890/1234567890 3 3 3

1234567890/1234567890 4 4 4

1234567890/1234567890 5 5 5

1234567890/1234567890 6 6 6

Total Transaction 7

PSIVIDA CORP.

THE COMPANY WILL FURNISH WITHOUT CHARGE TO EACH SHAREHOLDER WHO SO REQUESTS, A SUMMARY OF THE POWERS, DESIGNATIONS, PREFERENCES AND RELATIVE, PARTICIPATING, OPTIONAL OR OTHER SPECIAL RIGHTS OF EACH CLASS OF STOCK OF THE COMPANY AND THE QUALIFICATIONS, LIMITATIONS OR RESTRICTIONS OF SUCH PREFERENCES AND RIGHTS, AND THE VARIATIONS IN RIGHTS, PREFERENCES AND LIMITATIONS DETERMINED FOR EACH SERIES, WHICH ARE FIXED BY THE CERTIFICATE OF INCORPORATION OF THE COMPANY, AS AMENDED, AND THE RESOLUTIONS OF THE BOARD OF DIRECTORS OF THE COMPANY, AND THE AUTHORITY OF THE BOARD OF DIRECTORS TO DETERMINE VARIATIONS FOR FUTURE SERIES. SUCH REQUEST MAY BE MADE TO THE OFFICE OF THE SECRETARY OF THE COMPANY OR TO THE TRANSFER AGENT.

THE BOARD OF DIRECTORS MAY REQUIRE THE OWNER OF A LOST OR DESTROYED STOCK CERTIFICATE, OR HIS LEGAL REPRESENTATIVES, TO GIVE THE COMPANY A BOND TO INDEMNIFY IT AND ITS TRANSFER AGENT AND REGISTRAR AGAINST ANY CLAIM THAT MAY BE MADE AGAINST THEM ON ACCOUNT OF THE ALLEGED LOSS OR DESTRUCTION OF ANY SUCH CERTIFICATE.

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM - as tenants in common

TEN ENT - as tenants by the entireties

JT TEN - as joint tenant’s with right of survivorship and not as tenants in common

UNIF GIFT MIN ACT- Custodian

(Cust) (Minor)

under Uniform Gifts to Minors Act

(State)

UNIF TRF MIN ACT Custodian (until age)

(Cust) (Minor)

under Uniform Transfers to Minors Act

(State)

Additional abbreviations may also be used though not in the above list.

PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE

For value received, hereby sell, assign and transfer unto

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS INCLUDING POSTAL ZIP CODE OF ASSIGNEE)

Shares

of the common stock represented by the within Certificate, and do hereby irrevocably constitute and appoint

Attorney

to transfer the said stock on the books of the within-named Corporation with full power of substitution in the premises.

Dated: 20

Signature:

Signature:

Notice: The signature to this assignment must correspond with the name as written upon the face of the certificate, in every particular, without alteration or enlargement, or any change whatever.

Signature(s) Guaranteed: Medallion Guarantee Stamp

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (Banks, Stockbrokers, Savings and Loan Associations and Credit Unions) WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15.